JobLockService implementation

- Provides transaction-aware locking
 - Post-transaction cleanup is automatically done
 - Retrying for lock acquisition is handled internally as well
 - Downgraded the lock concurrency tests for the build machine (maybe 50 threads was too much)
 - Deadlock tests added for the high-level locking


git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/HEAD/root@13968 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261

source/java/org/alfresco/repo/lock/LockAcquisitionException.java

@@ -64,6 +64,7 @@ public class LockAcquisitionException extends AlfrescoRuntimeException
      * <ul>
      *   <li>1: the qname</li>
      *   <li>2: the lock token</li>
+     *   <li>3: the existing other lock</li>
      * </ul>
      */
     public static final String ERR_EXCLUSIVE_LOCK_EXISTS = "system.locks.err.excl_lock_exists";