LockscreenPattern : Toggle dots/error pattern visibility (2/2)

Give user ability to hide error pattern / dots.

Patchset 2 : Rebase
Patchset 3 : Remove debug msgs

Change-Id: Ie3904cdb3b59cd579b4713f85874ae2bac4e9dd1

Conflicts:
	res/values/strings.xml
	src/com/android/settings/SecuritySettings.java