Update submodules: plugins (new commits)

plugins:
    e2b1419 Greg Holmes <greg@dmdirc.com>
            EventBus logging for DCC plugin

            Gerrit: http://gerrit.dmdirc.com/3665

Change-Id: I81dd87665c8f757eb250f342eb000390edf7aa38
Update submodules: plugins (new commits)

plugins:
    490f027 Greg Holmes <greg@dmdirc.com>
            EventBus logging for FreeDesktop notifications plugin.

            Gerrit: http://gerrit.dmdirc.com/3667

    a32eced Greg Holmes <greg@dmdirc.com>
            EventBus logging for exec plugin.

            Gerrit: http://gerrit.dmdirc.com/3666

Change-Id: I0d0824530554b4ba9893ffca5cc2da5cc1b0b727