Fix ImapConnectionTest failure

[cketti]

Running tests outside of Android Studio started to fail for me with the following exception.

com.fsck.k9.mail.CertificateValidationException: java.security.cert.CertificateException: Certificates does not conform to algorithm constraints
	at com.fsck.k9.mail.store.imap.ImapConnection.handleSslException(ImapConnection.java:153)
	at com.fsck.k9.mail.store.imap.ImapConnection.open(ImapConnection.java:138)
	at com.fsck.k9.mail.store.imap.ImapConnectionTest.open_withStartTlsCapability_shouldIssueStartTlsCommand(ImapConnectionTest.java:669)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.robolectric.RobolectricTestRunner$HelperTestRunner$1.evaluate(RobolectricTestRunner.java:538)
	at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
	at org.robolectric.RobolectricTestRunner$2.evaluate(RobolectricTestRunner.java:339)
	at org.robolectric.RobolectricTestRunner.runChild(RobolectricTestRunner.java:259)
	at org.robolectric.RobolectricTestRunner.runChild(RobolectricTestRunner.java:41)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
	at org.robolectric.RobolectricTestRunner$1.evaluate(RobolectricTestRunner.java:199)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecuter.runTestClass(JUnitTestClassExecuter.java:114)
	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecuter.execute(JUnitTestClassExecuter.java:57)
	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassProcessor.processTestClass(JUnitTestClassProcessor.java:66)
	at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.processTestClass(SuiteTestClassProcessor.java:51)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:35)
	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
	at org.gradle.internal.dispatch.ContextClassLoaderDispatch.dispatch(ContextClassLoaderDispatch.java:32)
	at org.gradle.internal.dispatch.ProxyDispatchAdapter$DispatchingInvocationHandler.invoke(ProxyDispatchAdapter.java:93)
	at com.sun.proxy.$Proxy3.processTestClass(Unknown Source)
	at org.gradle.api.internal.tasks.testing.worker.TestWorker.processTestClass(TestWorker.java:109)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:35)
	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
	at org.gradle.internal.remote.internal.hub.MessageHub$Handler.run(MessageHub.java:377)
	at org.gradle.internal.concurrent.ExecutorPolicy$CatchAndRecordFailures.onExecute(ExecutorPolicy.java:54)
	at org.gradle.internal.concurrent.StoppableExecutorImpl$1.run(StoppableExecutorImpl.java:40)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)
Caused by: javax.net.ssl.SSLHandshakeException: java.security.cert.CertificateException: Certificates does not conform to algorithm constraints
	at sun.security.ssl.Alerts.getSSLException(Alerts.java:192)
	at sun.security.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1949)
	at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:302)
	at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:296)
	at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1514)
	at sun.security.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:216)
	at sun.security.ssl.Handshaker.processLoop(Handshaker.java:1026)
	at sun.security.ssl.Handshaker.process_record(Handshaker.java:961)
	at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:1062)
	at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1375)
	at sun.security.ssl.SSLSocketImpl.writeRecord(SSLSocketImpl.java:747)
	at sun.security.ssl.AppOutputStream.write(AppOutputStream.java:123)
	at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:82)
	at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:140)
	at com.fsck.k9.mail.store.imap.ImapConnection.sendCommand(ImapConnection.java:774)
	at com.fsck.k9.mail.store.imap.ImapConnection.executeSimpleCommand(ImapConnection.java:727)
	at com.fsck.k9.mail.store.imap.ImapConnection.executeSimpleCommand(ImapConnection.java:716)
	at com.fsck.k9.mail.store.imap.ImapConnection.requestCapabilities(ImapConnection.java:291)
	at com.fsck.k9.mail.store.imap.ImapConnection.startTLS(ImapConnection.java:334)
	at com.fsck.k9.mail.store.imap.ImapConnection.upgradeToTls(ImapConnection.java:315)
	at com.fsck.k9.mail.store.imap.ImapConnection.upgradeToTlsIfNecessary(ImapConnection.java:299)
	at com.fsck.k9.mail.store.imap.ImapConnection.open(ImapConnection.java:125)
	... 47 more
Caused by: java.security.cert.CertificateException: Certificates does not conform to algorithm constraints
	at sun.security.ssl.AbstractTrustManagerWrapper.checkAlgorithmConstraints(SSLContextImpl.java:1120)
	at sun.security.ssl.AbstractTrustManagerWrapper.checkAdditionalTrust(SSLContextImpl.java:1044)
	at sun.security.ssl.AbstractTrustManagerWrapper.checkServerTrusted(SSLContextImpl.java:986)
	at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1496)
	... 64 more

Returning the TLS certificate the mock server is using from VeryTrustingTrustManager.getAcceptedIssuers() is fixing this issue for me.

[Valodim]

Current master tests fine for me. Changes look good though, and only affect test classes so that's fine