Add unpackbootimg.

Change-Id: I9e3e279e2b48b3fdf5b64a7e9a28fa54e91ccace
unpackbootimg: Add support for device trees

Change-Id: I340eed99d2274a2f4cbaf5a9f27726ff3a9302e5
Merge remote-tracking branch 'cm/android-4.4' into android-4.4