Update submodules: plugins (new commits)

plugins:
    a1c4652 Chris Smith <chris@dmdirc.com>
            Fix some nonsense in the LoggingManager.

            Don't get a random Object only to toString() it later, just use strings.
            Don't rely on toString() existing across different implementations.
            Don't try and find a log file for servers, they don't exist.

            Gerrit: http://gerrit.dmdirc.com/3878

    70d1876 Chris Smith <chris@dmdirc.com>
            Replace servers with connections.

            Gerrit: http://gerrit.dmdirc.com/3874

Change-Id: I10376e486880dbe933d2b19bbe766e88dd909093