version: upstream dirty is nightly

Previously the upstream dirty builds were released using a pre-release
versioning (prefixing a 0). This doesn't fit the release process in
which the upstream builds are nightly.

More information on pre-releases at:

http://fedoraproject.org/wiki/Packaging:NamingGuidelines#Pre-Release_packages

In this patch:

* remove the leading 0 used for pre-releases (instead of nightly)
* remove vdsm.spec on make clean
* use any tag (not just the annotated ones) to identify the release

Change-Id: Ibbf52173ccaa4a4eb0de5aa2cf61f821ba1fa215
Signed-off-by: Federico Simoncelli <fsimonce@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/14954
Reviewed-by: Kiril Nesenko <knesenko@redhat.com>
Tested-by: Kiril Nesenko <knesenko@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>