Fix issue #2530103: ActivePassword data in Device Policy Manager needs to be persisted

Also fixes how the quality vs. mode is handled to be more consistent, which also
required introducing a new "alphabetic" quality since it is possible for the user
to enter such a password.

The current password quality and length is stored in the DPM, since at boot it
couldn't figure this out from the stored password.

Change-Id: I519d9b76dd0b4431bcf42920c34dda38c9f1136e