Add Google to the AUTHORS file.

Change-Id: Ie1c882a622cf8f4de12230367b11a644d3040ae8
Reviewed-on: http://gerrit.dmdirc.com/2642
Automatic-Compile: DMDirc Build Manager
Reviewed-by: Greg Holmes <greg@dmdirc.com>
Update submodules: plugins (new commits)

plugins:
    b982c81 Greg Holmes <greg@dmdirc.com>
            Show and hide topic bar appropriately.

            Fixes-Issue: CLIENT-401
            Gerrit: http://gerrit.dmdirc.com/2637

Change-Id: Ief1d41b23442577aad8c07f8abf904511dcb4cc6