* Make first /dev/loop0 device at archiso install hook.
* Remove unneeded losetup, all is done directly via mount.
* Images are now mounted on /tmpfs/mnt/image-name instead of
/tmpfs/mnt/loopN, removing unneeded counter.
* Add some variables to make code more readable.

Signed-off-by: Gerardo Exequiel Pozzi <vmlinuz386@yahoo.com.ar>