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.
ACCUMULO-841 Refactor randomwalk State class

* Create new Environment object, separate from State, for config props and client objects
* Update most randomwalk test nodes and framework to use Environment
* Eliminate State visit counting, which is unused and redundant with Module's maxHops
* Move getMapReduceJars() method to Node
* Move getPid() method out of State
* Eliminate getCredentials() which ends up not useful
* Reduce visibility to several methods in State and Environment
ACCUMULO-2391 hide warning if it takes just one retry
Merge branch '1.6.0-SNAPSHOT'

Conflicts:
	server/tserver/src/main/java/org/apache/accumulo/tserver/log/TabletServerLogger.java
ACCUMULO-2393 handle table deletion race condition
Merge branch '1.6.0-SNAPSHOT'
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
Merge branch '1.5.1-SNAPSHOT' into 1.6.0-SNAPSHOT
Merge branch '1.6.0-SNAPSHOT'
ACCUMULO-2170 One more update to CHANGES
Merge branch '1.5.1-SNAPSHOT' into 1.6.0-SNAPSHOT
Merge branch '1.6.0-SNAPSHOT'
[maven-release-plugin] prepare release 1.5.1
ACCUMULO-2397 dirty the !METADATA table a second time to ensure the file list changes
Merge branch '1.6.0-SNAPSHOT'
ACCUMULO-2170 Update year in copyright NOTICE.
Merge branch '1.5.1-SNAPSHOT' into 1.6.0-SNAPSHOT
Merge branch '1.6.0-SNAPSHOT'
ACCUMULO-2398 write more data, wait less between checks
Merge branch '1.6.0-SNAPSHOT'