Add repopick script from CM

patchset 4: cybojenix
  clean up the script:
    remove fetching from github
    cleaned up fetching locations of binaries
    if ANDROID_BUILD_TOP isn't defined, error out

PS 5:
  Added back the check if fetch succeeded.
  Fixed verbose print about fetching.

patchset 6:
  final changes
    fix detecting ANDROID_BUILD_TOP
    send all relavant data to stderr

Change-Id: If67c5f178d03fadd8b79b1908f4a9cb231efbb28
Merge branch 'android-4.3' of https://github.com/omnirom/android_build into HEAD