Quick unlock : Fix bug

There is an issue where users whose passwords are greater than 8 chars and
have quick unlock enabled will be unable to unlock their lockscreen.
This is due to the logic evaluating anything beyond 3chars as a password attempt.

This change modifies the quick unlock behavior so that when typing the password,
each character is considered an attempt, however if incorrect, is not reported as a failed attempt.
Only when the user presses enter is it considered an "explicit" attempt and a failed attempt is reported.

Patchset 2 : Rename runnable to better reflect its purpose
Patchset 3 : Switch to new behavior
Patchset 4 : Fix padding

Change-Id: Ida6289c77f6724cb42e8d3b82593f29afe3d6d1b