vendor/custom: Backuptool files

This goes along with the releasetools enhancements in build/

Based on CyanogenMod 10.1, but debranded to generic naming for
easier sharing between community projects

Change-Id: I7031af3372a0bda31397e68761f772eccd4cb138

Omni: Update backuptools version

Change-Id: I94ea75203b35a68b4580310f510e20b70fc2b204