Support for plugins building using ivy.

Change-Id: I34d7849a75cd4c7a91e04a9dad6f8073aa5a8f61
Depends-On: I65d96f91e1eb5ed7afb43dd41cd00531d809878d
Reviewed-on: http://gerrit.dmdirc.com/2735
Automatic-Compile: DMDirc Build Manager
Reviewed-by: Greg Holmes <greg@dmdirc.com>
Update submodules: plugins (new commits)

plugins:
    c2e9460 Chris Smith <chris@dmdirc.com>
            Use ivy for plugin dependencies.

            Depends-On: I34d7849a75cd4c7a91e04a9dad6f8073aa5a8f61
            Gerrit: http://gerrit.dmdirc.com/2736

Change-Id: I9503fe4259c403a32c2caeabd9b8ae0bf4335f45