Improve algorithm to match Git users with GitHub users

The idea is to:

• Search for a user with the passed login. Note: We don't use "gitHub.getUser(authorId)" because if the authorId is a simple one (like "Gabriela") then it's very likely that it'll return the wrong user. Doing a search is likely to return more than one user and thus we'll search with the email address and full name.
• Search for a user with a matching email address
• Search for a user with a full name matching the passed login (since on git, sometimes users set their name as their git id).