This should help with debugging by providing better information on which
Pungi version created the compose. In development, the version will show
output of git describe, in production it asks which version is installed
in site-packages/. The egg-info directory must be installed for this to
work.
It is no longer necessary to synchronize version in `setup.py` with
`pungi/__init__.py`.
Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>