Don't put credentials in results from externally accessible activities

ConfirmLockPattern and ConfirmLockPassword return an intent that contains the
password, and as such are dangerous. Create internal versions that are locked
down, and don't put this info in the externally accessible versions.

Bug: 13741939
Change-Id: I0df4d1e720b3c33d2c9ca086636dc54f17b19bf0