Merge branch '1.6.1-SNAPSHOT' of https://git-wip-us.apache.org/repos/asf/accumulo into 1.6.1-SNAPSHOT
ACCUMULO-2862 stop re-throwing CompactionInteruptedException, wrote a test to verify that splits interrupt major compactions
ACCUMULO-1919 add missing import
ACCUMUMLO-2255 more little cleanups and class extractions
ACCUMULO-2753 used TServerInstance to encode mutations
ACCUMULO-2876 Use site config to configure default VolumeManagerImpl

This changes VolumeManagerImpl.get() to use the site configuration instead of the
ZooKeeper-based system configuration. This seems to align better with what is intended,
and it also eliminates the risk of an infinite loop, where the system configuration
requires an HdfsZooInstance instance ID, which requires a volume manager.
Merge branch '1.6.1-SNAPSHOT'
ACCUMUMLO-2255 rat check failures
Merge branch 'master' of https://git-wip-us.apache.org/repos/asf/accumulo