Trebuchet: Lock homescreen

Allow lock shortcuts and folders positions in the workspace, hotseat and apps and widgets drawer.
When is enabled the system avoids to move any shortcut or folder, change its names and
access to widgets.

Patchset 2: Fixed typo

Change-Id: I832da526cf1eb32752218656a7c2dafc53010236
JIRA: CYAN-686
Issue: https://jira.cyanogenmod.org/browse/CYAN-686
Signed-off-by: Jorge Ruesga <jorge@ruesga.com>