Add GitHub integration

[Arlodotexe]

The problem

If users want to contribute to Labs, Uno or another open source project as part of the Appathon, the user would need to be added by the maintainer for our collaboration system to track their contributions. This should be automatic.

The solution

Pull contributor information from the git repo itself and match the email addresses with known addresses from users.

• Users should be able to link their community account to GitHub
• Enable the user to link a project directly to a github repo
• Backend should be able to scan the repo for a contributor list
• Write a recurring task does the scan and caches information about contributors. Needed for large projects like Uno.