(1/2)Cherry-pick before build
(ported from the pac-4.4 branch)

This will enable us to specify gerrit commits not yet merged
to be cherry-picked before build starts

-All local branches will be abandoned before the cherry-picking
starts (unless the -b switch is removed from cherries.sh)
-There are two sections in the cherries.sh file. The first
is where cherries are added that are applicable to any device.
Inside the case statement, cherry-picks can be specified per
device or range/set of devices.
-If a build is started with the -f switch and there are no
global or device specific cherry-picks, the cherry-pick tool
will not be called.
-Cherry-picks are specified by quoting the gerrit change
number followed by an underscore and the gerrit account acronym.

PS1: Ported from cm-10.2 branch
PS4: Rebased
PS5: Rebased
PS6: Bring over cherries.sh
- update LX cherries

Change-Id: If78c8f99ec1512b9a9671ec15846c0d28e7c1c70