Support for Bitbucket and others?

[mbergenlid]

This really looks like a promising tool that I'd like to use. Unfortunately, we use Bitbucket and not Github at work so it would be nice to make that "pluggable". Having looked through the code it seems doable by replacing the Github struct with a generic trait.

Seems to require a bit of refactoring but I was thinking of forking this and give it a go so that at least I could try using the tool. Would you be interested in receiving PRs for such a change?

[systemsoverload]

Im actually a dev for Bitbucket Cloud and looking into using this tool for some internal tools. Considering doing something like adding an SCMProvider trait and making the commands generic over the trait type. Is there an appetite for a change like that upstream? If not, we can just fork and delete the github backend.