Exception on flexible staging

[etanshaul]

The following occurs do to an invalid path to the deployment artifact during flexible staging. This should not occur during normal execution:

• If the deployable is an artifact deployment source, then the internal platform should correctly pick up the deployable path
• If the deployable is a maven source, then the path is picked up by the maven plugin

At a minimum we should should present the exception message "/a/b/c.jar (The system cannot find ...)" to the user in the deployment console in IJ.

Description:
java.io.FileNotFoundException
Device Model:
unknown

Device Release:
2016.2

App Version:
2016.2

Stack trace:
java.lang.RuntimeException: java.io.FileNotFoundException:
(The system cannot find the path specified)
at com.google.cloud.tools.intellij.appengine.cloud.AppEngineFlexibleStage.stage(AppEngineFlexibleStage.java:81)
at com.google.cloud.tools.intellij.appengine.cloud.AppEngineFlexibleDeployTask.execute(AppEngineFlexibleDeployTask.java:67)
at com.google.cloud.tools.intellij.appengine.cloud.AppEngineRunner.run(AppEngineRunner.java:39)
at com.intellij.openapi.application.TransactionGuardImpl$6.run(TransactionGuardImpl.java:291)
at com.intellij.openapi.application.impl.LaterInvocator$FlushQueue.a(LaterInvocator.java:326)
at com.intellij.openapi.application.impl.LaterInvocator$FlushQueue.run(LaterInvocator.java:310)