Refactor overlay paths

as had been discussed, and as Brandon has already done with his d2 repos.

this should help in reducing a lot of redundancy between devices of a family as we  can keep common overlays in overlay/<OEM>/*common directories


Change-Id: Ice84703bb73f462a2ecc65e46b0a65e16392adfa
Signed-off-by: ChampionSwimmer <championswimmer@aokp.co>
Merge "Refactor overlay paths" into kitkat