HBASE-7550 Synchronization problem in AssignmentManager

git-svn-id: https://svn.apache.org/repos/asf/hbase/branches/0.94@1432806 13f79535-47bb-0310-9956-ffa450edef68
HBASE-7468 TestSplitTransactionOnCluster hangs frequently

git-svn-id: https://svn.apache.org/repos/asf/hbase/branches/0.94@1432808 13f79535-47bb-0310-9956-ffa450edef68