trebuchet: Fix shortcut install/uninstall permission name

AOSP 4.4 has a public INSTALL_SHORTCUT/UNINSTALL_SHORTCUT permission.

Change-Id: I11cf09b4964838b2366ec37646392ff61be6c529
Signed-off-by: Jorge Ruesga <jorge@ruesga.com>
Merge remote-tracking branch 'cm/cm-11.0' into cm-11.0