ACCUMULO-3269 Set REUSEADDR on the Socket.

Setting SO_REUSEADDR on the Socket used to ask
ZooKeeper if "it's ok" appears to help mitigate
the spurious issue when ZooKeeper would fail to
bind to an otherwise free port.
Merge branch '1.6'
ACCUMULO-3306 Remove unused import
ACCUMULO-3269 Add a brief sleep before retrying ruok
Merge branch '1.6'
ACCUMULO-3394 Consolidate thrift related classes in one package.
ACCUMULO-3394 Remove unused method.
ACCUMULO-3394 Update some documentation.
ACCUMULO-3394 Fix up whitespace