build-scripts: monster re-write of build scripts. Based on ktoonsez's

Change-Id: I1bb897bc690d0be6d236ec22e0a82bebbf09238b

Conflicts:
	build-all-variants.sh
	build-att-tw.sh
	build-eur-tw.sh
	build-spr-tw.sh
	build-tmo-tw.sh
	build-vzw-tw.sh
Remove + from Kernel version if LOCALVERSION_AUTO is not set

Change-Id: I6562f896bb93c679f00107fa9ee719b5c567d784