Merge branch '1.6' of https://git-wip-us.apache.org/repos/asf/accumulo into 1.6
ACCUMULO-3183 support loading compaction strategy from per table classpath
ACCUMULO-3189 add verification of compaction plan
Merge branch '1.6'

Conflicts:
	core/src/main/java/org/apache/accumulo/core/conf/Property.java
	server/tserver/src/main/java/org/apache/accumulo/tserver/tablet/Tablet.java
ACCUMULO-3193 use a thread pool to jam more requests into the NN, which will hopefully compete better with the other NN requests
Merge branch 'master' of https://git-wip-us.apache.org/repos/asf/accumulo