gbp.conf: upstream branch is upstream-31.x

Git-Dch: Ignore
Imported Upstream version 31.2.0
Merge tag 'upstream/31.2.0'

Upstream version 31.2.0

# gpg: Unterschrift vom Mo 27 Okt 2014 18:07:17 EDT mittels RSA-Schlüssel ID A74420EF
# gpg: Korrekte Unterschrift von "Christoph Goehre <christoph.goehre@gmx.de>"
# gpg:                     alias "Christoph Goehre <chris@sigxcpu.org>"
rebuild patch queue from patch-queue branch
adjust icedove depends to >= 31.2.0 and << 32
linitan: bump up standards version to 3.9.6
document changes and release 1:31.2.0-1
debian/control: fix recommends for icedove-l10n-sr

As pointed out by Jonas Smedegaard the field Recommends for
icedove-l10n-sr was wrong. Corrected as suggested by Jonas.

Closes: #767635