Cleanup removed submodules

[sslavic]

I've removed some submodules from the project, and running versioneye update did not clean them up. I had to manually "unmerge" submodules via UI. It would be nice improvement to do this automatically, or at least to be able to control/enable this behavior via a feature flag.

[reiz]

Hi @sslavic makes sense! I put this on our Roadmap. Should be finished in the next weeks.