build: Add support for extra kernel build variables

* This allows specifying a variant defconfig, and an selinux defconfig
   which are simply configuration fragments.

Merged from original commit:
https://github.com/CyanogenMod/android_build/commit/c102a65dfab65b7aed9d21377f238f0cb2cb78be
Fix module compiling errors for galaxy devices

:)
Merge pull request #3 from pcarenza/jb-mr1

clearer progress bar, more verbose install messages
Merge pull request #4 from Black-Prince/jb-mr1

Fix module compiling errors for galaxy devices
added phasebeam to packages
fix SunBeam