Update submodules: plugins (new commits)

plugins:
    be7ceba Chris Smith <chris@dmdirc.com>
            Make versioning work regardless of the root.

            Also make some things more groovy-y.

            Gerrit: http://gerrit.dmdirc.com/4029

Change-Id: I5cc39a51c20ad0334df4e4599389a0b99e3f0ef5