ACCUMULO-2390 InvocationTargetEx in TraceProxy

Handle InvocationTargetException specifically in TraceProxy, instead
of letting it get propogated up the call stack. In some cases this is
very bad as it turned into an UndeclaredThrowableException and made
debugging more difficult than necessary.

Added unit test to verify behaviour.
Merge branch '1.4.5-SNAPSHOT' into 1.5.1-SNAPSHOT

Conflicts:
	src/trace/src/main/java/org/apache/accumulo/cloudtrace/instrument/TraceProxy.java
	src/trace/src/test/java/org/apache/accumulo/cloudtrace/instrument/TracerTest.java