Update submodules: plugins (new commits)

plugins:
    d66a4d7 Chris Smith <chris@dmdirc.com>
            Use gradle wrapper.

            I haven't tested with windows stuff... :)

            Gerrit: http://gerrit.dmdirc.com/3896

Change-Id: If6e58be5e58ddadfd477ca7926c31b23e1db358c