Trebuchet: Remove workspace items of hidden apps

Remove the shortcut and widget associated to an app when this become hidden
for user setting.

Change-Id: I4ce8f545ef879d711fbbd8ab8572dcd7386dfa75
Signed-off-by: Jorge Ruesga <jorge@ruesga.com>
Merge "Trebuchet: Remove workspace items of hidden apps" into cm-10.1