[createiso] Use shell script for runroot

Instead of installing pungi itself in the runroot, we can prepare the
commands to be run on compose box, write the shell script into work/
directory, which is mounted in the chroot, and execute that. This way
there is no business logic in runroot (except for finding lorax
templates).

The main advantage of this approach is that we don't need to pull any
extra dependencies into buildroot.

Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>

setup.py

@@ -41,7 +41,6 @@ setup(
         'bin/pungi-fedmsg-notification',
         'bin/pungi-koji',
         'bin/pungi-make-ostree',
-        'bin/pungi-pylorax-find-templates',
     ],
     data_files      = [
         ('/usr/share/pungi', glob.glob('share/*.xsl')),