Update submodules: plugins (new commits)

plugins:
    ca1d401 Chris Smith <chris@dmdirc.com>
            Remove pointless override.

            Gerrit: http://gerrit.dmdirc.com/3385

Change-Id: I815584a6561d84b86b1d4510e5b20e6d4d487170
Couple of test additions/improvements

Change-Id: Id0c8eedd2654afd9590cc2520dcafa889b053e16
Reviewed-on: http://gerrit.dmdirc.com/3387
Automatic-Compile: DMDirc Build Manager
Reviewed-by: Greg Holmes <greg@dmdirc.com>