This generates a repository in either v5 or v6 and adjusts
the name/vendor attributes accordingly.
This extracts the support extra in a separate 'repo-extras.xml'
which has an addon.xsd type instead of being a repository.xsd.
Requires sdk.git change Ib0363f06 to build properly.
Change-Id: I250fe7a3ec0dfa490778ae747a1a8f4e536bb395
Also fix packaging of system image (it had an extra root
directory in it, e.g. it was packaging android-4/armeabi-v7a/
instead of just armeabu-v7a/)
Change-Id: I0254b2680168d25103222f8871b2af37a7406b58
