OAK-2123: Tests do not tear down repository completely

Merge revision 1627479 from trunk

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/branches/1.0@1627480 13f79535-47bb-0310-9956-ffa450edef68
OAK-2120: Simplify BranchStates

Merged revision 1627047 from trunk

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/branches/1.0@1627481 13f79535-47bb-0310-9956-ffa450edef68
OAK-2127: Long running merge may block other commits

Merge revision 1627346 from trunk

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/branches/1.0@1627482 13f79535-47bb-0310-9956-ffa450edef68