ENG-591 Dispose ClusteredEntityManager during CacheManager shutdown

git-svn-id: http://svn.terracotta.org/svn/ehcache@8406 b9324663-ca0f-0410-8574-be9b3887307d
ENG-488 CacheException when adding clustered Cache to non clustered CacheManager

git-svn-id: http://svn.terracotta.org/svn/ehcache@8407 b9324663-ca0f-0410-8574-be9b3887307d
merge from trunk up to r8407

git-svn-id: http://svn.terracotta.org/svn/ehcache@8408 b9324663-ca0f-0410-8574-be9b3887307d
ENG-491 Read lock ClusteredCacheManager entity, create entity under write lock

git-svn-id: http://svn.terracotta.org/svn/ehcache@8409 b9324663-ca0f-0410-8574-be9b3887307d
ENG-488 Fix unit test that was triggering added exception

git-svn-id: http://svn.terracotta.org/svn/ehcache@8410 b9324663-ca0f-0410-8574-be9b3887307d