instant locking support

A timeout value of 0 triggers a lock event immediately.
handle disconnections properly

checkCacheWordState() should never be called when cache word is disconnected
Fix SecureRandom vulnerability

http://android-developers.blogspot.com/2013/08/some-securerandom-thoughts.html
fix service connection race condition resulting in ghost subscribers

If a connect and disconnect are received before the connection has
time to complete, the connection would complete AFTER it should have
already disconnected. The result was that CacheWordService never received
the detachSubscriber call, so the mSubscriberCount became inaccurate.
the persistent unlocked notification can now be disabled