Manage and fetch users' organizations
Remove all about "collaborators"

As the collaborators stuff in github is not always exactly the same
thing, we don't fetch them anymore, and display a more precise list of
users for filter by creator/assigned/closed_by
Save the private flag when syncing repositories
Fetch and save available repositories of an authenticated user
Restore collaborators to use in issue comments
Add github authentication

And ultra basic home and dashboard pages