gbp.conf: added for easier living while preparing the package

Adding a gbp.conf for getting stuff easier maintained, like the
pristine-tar commit or creating the changelog with 7 digits of the
commit id.
Imported Upstream version 31.0
Merge tag 'upstream/31.0'

Upstream version 31.0

# gpg: Unterschrift vom So 27 Jul 2014 19:01:10 CEST mittels RSA-Schlüssel ID 251D1DB0
# gpg: Korrekte Unterschrift von "Carsten Schoenert <c.schoenert@t-online.de>"
rebuild patch queue from patch-queue branch