packaging: setup: Removing build-conf files on failure

If setup fails it should cleanup the partially deployed files
in order to allow a future clean setup.
If those files were already there it restores the backup
copy of the older ones, otherwise it simply removes the
new files.

Change-Id: I2507ea0c6ecd6d0a69f56d0693fcafd21f58992f
Bug-Url: https://bugzilla.redhat.com/1091700
Bug-Url: https://bugzilla.redhat.com/1084749
Signed-off-by: Yaniv Dary <ydary@redhat.com>