Attempt to fix md5 issue with backups

thanks @bigbiff for the suggestion

Change-Id: Ie9b55537b7fa300461b015d2b9523d4250e755a9
Update RECOVERY_VARIANT blocking to use project-path-for

Using RECOVERY_VARIANT to allow recovery to reside at
bootable/recovery-(variant) has changed at CM. project-path-for now
handles all the path re-mapping. This is simply a compatibility update
to be able to continue using RECOVERY_VARIANT with TWRP in a CM tree.

Change-Id: I66769d85b2a111e837f206b1c9a5bc07d6ac0d86
Merge remote-tracking branch 'omni/android-4.4' into android-4.4