Build - add support for overriding build.prop settings.

Change-Id: I4ff3f6311832578f1d7b430beb6c577203fb8bb6
Signed-off-by: STELIX <ssspinni@gmail.com>
Build - add support for custom releasetools

Change-Id: Id638bdb418360746bdc0a34d92ada1f6f15ea92f
Signed-off-by: STELIX <ssspinni@gmail.com>