Extract SourceControl subdirectory to gem?

Hey @guilhermesimoes or whoever else is working on rubycritic these days!

I've continued working on Debt Ceiling off and on the last year or so, and just finished a v1 of a big new feature... It adds/requires additional git/source control dependency, and while I considered using rugged, I decided to look at what you guys did for git code and liked your source control abstraction as a light weight interface with no additional dependencies...

For now I just copy pasted your code into my repo and built some new features on it, but I wondered if you would be open to/interested in making it into a new shared gem we can both rely on together? Or, it just occurred to me to see if anyone else already has a ruby source control abstraction, we might both be able to rely on this scm gem I just found, but my addition to your library would need to be ported to theirs, and I think will only work for git... Curious for thoughts/reactions, the PR with my changes to your code are here starting with base.rb, but missing implementation for travel_to_commit for mercurial, and some test coverage. Just an initial feeler while I ponder next steps.

Start by reviewing the linked Debt Ceiling pull request, especially the changes beginning with base.rb, and compare them with Rubycritic's existing SourceControl code. Check the missing travel_to_commit implementation for Mercurial and the stated test-coverage gap. Done would require a decided extraction or integration plan, including compatible implementations and tests.