ACCUMULO-2128 added utility to cleanup accumulo static resources

Signed-off-by: Keith Turner <kturner@apache.org>
ACCUMULO-2128 added waitForZooKeeperClientThreads method

Signed-off-by: Keith Turner <kturner@apache.org>
ACCUMULO-2128 added test for static clean up utility
Merge branch '1.4.5-SNAPSHOT' into 1.5.1-SNAPSHOT

Conflicts:
	core/src/main/java/org/apache/accumulo/core/client/impl/ThriftTransportPool.java
	fate/src/main/java/org/apache/accumulo/fate/zookeeper/ZooSession.java
Merge remote-tracking branch 'origin/1.5.1-SNAPSHOT' into 1.6.0-SNAPSHOT

Conflicts:
	core/src/main/java/org/apache/accumulo/core/client/impl/ThriftTransportPool.java
Merge branch '1.6.0-SNAPSHOT'
ACCUMULO-1976 Fix upgrade broken by ACCUMULO-2093
Merge branch '1.6.0-SNAPSHOT'