LockScreen: Fix crash when unlocking twice

This will keep track if the BroadCastReceiver is registered and
will unregister it only if so.

Change-Id: I040d710cf0927394f36b2e3da251ac5a988ce1d6
Signed-off-by: Dirk Rettschlag <dirk.rettschlag@gmail.com>
Lockscreen Longpress: Unlock Logic

In my opinion, we should unlock after
    user removes their finger.
This matches short-press unlock better
    and allows the user to change their mind
    on a target (I do that a lot).
Added a vibration action on longpress
    being true.

Change-Id: Ife590119dbdf10474b9c62f252e7f5d6dfc87387