Rough draft of the Committing guidelines

This is the rough draft and will have many more changes as we flesh out exactly what we want our committing standards to be.
Note: the Robottelo Standards link will be broken until we create that document.
See about halfway through [this message](https://github.com/SatelliteQE/robottelo/issues/1354#issue-42572822), after the paragraph stating "What should be on the checklist?"