vendor/aicp: Backuptool files (from omni)

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

PS2:
- Set correct ro.build.version.release version in backuptool.sh
- removed nonexistant config/common.mk
- added correct copy lines to our common.mk
- removed 50-hosts.sh script, it's not used anywhere and even Omni has error in their common.mk to copy 50-examples.sh and not hosts file :D
- to calm your nerves, we have hosts persistance support under RC

PS3:
- vendor/custom -> vendor/aicp -I'm worts than Peter in copy/paste

PS4:
- set proper andoid version for backup script pre-check

Change-Id: I6d26221c02a53296b29ce0d90a912bb6e74065fc