Implement `commit` action

[lcidral]

As suggested by @amadeu01 we can introduce a git pair commit github-username that will open COMMIT_MSG file to write commit title and message then will append only this given github-username ignored the users that you're pairing with.

WDYT?

[amadeu01]

I think this option is really nice and it can be even better for users that do not want to mess with their already existent hook scripts.