fix entity id with constant tags

[dbyron0]

Before this change I see:

Tests run: 56, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 4.936 sec <<< FAILURE!
sends_gauge_entityID_from_env_and_constant_tags(com.timgroup.statsd.NonBlockingStatsDClientTest)  Time elapsed: 0.004 sec  <<< ERROR!
java.lang.ArrayIndexOutOfBoundsException: 2
	at com.timgroup.statsd.NonBlockingStatsDClient.updateTagsWithEntityID(NonBlockingStatsDClient.java:1291)
	at com.timgroup.statsd.NonBlockingStatsDClient.<init>(NonBlockingStatsDClient.java:632)
	at com.timgroup.statsd.NonBlockingStatsDClient.<init>(NonBlockingStatsDClient.java:364)
	at com.timgroup.statsd.NonBlockingStatsDClient.<init>(NonBlockingStatsDClient.java:238)
	at com.timgroup.statsd.NonBlockingStatsDClientTest.sends_gauge_entityID_from_env_and_constant_tags(NonBlockingStatsDClientTest.java:479)
	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$1.runReflectiveCall(FrameworkMethod.java:50)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.junit.internal.runners.statements.FailOnTimeout$CallableStatement.call(FailOnTimeout.java:298)
	at org.junit.internal.runners.statements.FailOnTimeout$CallableStatement.call(FailOnTimeout.java:292)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.lang.Thread.run(Thread.java:748)

[ogaca-dd]

@dbyron0: Thank you very much for your contribution!

[dbyron0]

Any plans to release a version with this fix?