Pass dependencies in to the UpdateChecker.

Keep the existing hackery until the plugins that call it are updated.

Change-Id: Ia7e89f9d3de662451ccbec04eabf453478e256c1
Reviewed-on: http://gerrit.dmdirc.com/3028
Automatic-Compile: DMDirc Build Manager
Reviewed-by: Greg Holmes <greg@dmdirc.com>
Update submodules: plugins (new commits)

plugins:
    6647d09 Chris Smith <chris@dmdirc.com>
            Update plugins to pass state into UpdateChecker.

            Gerrit: http://gerrit.dmdirc.com/3029

Change-Id: I55dd8451660ed7210df6fa0c968440aae1dcb9a2