Add api-resource-locks feature

Add api-resource-locks feature

Added ResourceLockFeatureAPI, to provide an interface for PolicyGuard
to use to access other locking mechanisms.
Move lock API to policy-core.
Changed the interface and added Callback support.  Added a class to
invoke the API implementers.
Changed to set a future instead of expecting the callback to implement
the future interface. Also refactored, creating "lock" sub-package.
Add junit tests.
Increase junit coverage.
IsLocked & isLockedBy should check all arguments.
Make ImplFuture protected instead of public.
Simplify locking - move callback support to an optional feature.
Move Reference class to policy-utils.
Return plain Future instead of LockRequestFuture.

Change-Id: I65154d33833914b4332e02d1ef2512f4c5f09b16
Issue-ID: POLICY-577
Signed-off-by: Jim Hahn <jrh3@att.com>