EventBus the prefs events.

Change-Id: Ia3a86ce30a3ad96c2c67597dba341b2b10162c8e
Depends-On: I27e1059cc3228013d30bab85549434dea28f236c
Reviewed-on: http://gerrit.dmdirc.com/3417
Automatic-Compile: DMDirc Build Manager
Reviewed-by: Chris Smith <chris@dmdirc.com>
Update submodules: plugins (new commits)

plugins:
    e257d4a Greg Holmes <greg@dmdirc.com>
            Eventbus the prefs events.

            Depends-On: Ia3a86ce30a3ad96c2c67597dba341b2b10162c8e
            Gerrit: http://gerrit.dmdirc.com/3418

Change-Id: I5c19d773f5319e842f0560da8061b02abf9f262b