kickstart %pack and %attachemnt sections and btrfs command [zypp] Simplify pattern unrolling in zypp backend

* %pack is a new script section that gets run after the image
has been packed and moved to outdir.

* IMG_OUT_DIR is exported to %pack and %post scripts' environment.

* Make %attachment section usable in all image types not only loop
mic supports %attachments section where items to be extracted from image can be added.

* Items in the %attachment section can be :

** absolute file paths starting with '/' are copied from inside the image rootfs
** name of rpm already installed in the rootfs; expanded to a filelist and all of them extracted
** if the rpm is not already installed download will be requested from package manager
  (with repos from kickstart) and then unpacked ( not installed in image )

* Backport btrfs command from Fedora's Anaconda (https://fedoraproject.org/wiki/Anaconda/Kickstart#btrfs)
for loop images. Raw images have a mic specific btrfs implementation that is now considered deprecated
and will be replaced. Some extensions to the fedora command were added:
* --parent option is used to match subvolumes to parent volume / partition
* --quota option turns on quota in the volume before creating the subvolumes
* --snapshot creates a snapshot from the subvolume specified by --base

Signed-off-by: Islam Amer <islam.amer@jollamobile.com>