[BUILD] Opened release branch 13.12.6

Change-Id: I1ee8776db1fd77640d9baca40c31346ea2d01039
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1257
Tested-by: Jenkins CI
Reviewed-by: Franz Zieris <zieris@inf.fu-berlin.de>
[FIX] invitation page displays null when no nickname is available

Trivial fix, just use the base part of the JID when no nickname is
available.

Change-Id: I3a4c4b72081ce91c5ee6c0ac5ae005e0714ba398
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1261
Reviewed-by: Nils Bussas <nils.bussas@gmail.com>
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>
[BUILD] Prepared Beta-Update site for 13.12.6

The version number is 13.12.6.TESTING

Change-Id: Ibbbad392792a9f2fd9ba9868d5f24a874d85f0a4
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1285
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>
Reviewed-by: Franz Zieris <zieris@inf.fu-berlin.de>
[BUILD] Put last state of the update-site under version control

During the release 13.3.22 we forgot to put the changes that were
present on the webserver under version control. This patch catches up on
that.

Change-Id: Ib425456f70914ada12019b383da28a9932e9fa1e
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1287
Tested-by: Jenkins CI
Reviewed-by: Franz Zieris <zieris@inf.fu-berlin.de>
[BUILD] Changes necessary for Release 13.12.6

This patch updates:
 * Version numbers
 * Feature description
 * Update-site
 * Changelog
 * Credits

Change-Id: Ife69291d3e06dae43b5bf9f500aa3cb83192a4db
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1286
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>
Reviewed-by: Andrej Szaffranietz <a.szaffranietz@gmail.com>
Reviewed-by: Franz Zieris <zieris@inf.fu-berlin.de>
[BUILD] Merged 'release/13.12.6' back into 'master'

Change-Id: Ia553fa982f8acf17c6b48401366e14bd2a200f85