Jellybean

Note: default behavior should be the same as before!
 
* Rename build script from rom-build.sh to build.sh
* Fixed cosmetic issues
* Control PAPrefs build/install procedure by environment variable
* New features:
  - ccache support (works with prebuilt ccache but works much better with system one, requires changes to "build")
  - prebuilts support (requires prebuilts chnages to "vendor_pa")
  - interactive shell
  - save build manifest (like CM do, for better re-constructibility)