Git conventions

[ifraixedes]

We don't have Git conventions defined in this repository and they may lead to:

• Having discussions on the same topics over and over.
• Having discussions of different approaches where none of them are wrong and it's a matter of personal tastes.
• Ending up having a not neat Git commit history.

The purpose of this issue is to discuss different approaches to working with Git and reach a consensus to establish some conventions for not having the issues listed above.

At least we should agree on:

• Git commit message conventions.
• Git merge strategies.
• Who is responsible to merge an approved commit / PR?