Updating authentication scope, repo list and adding blacklist

[ghost]

Sorry for the multiple commits, let me know if you want me to split them into separate pull requests (branching, cherry picking etc). This is what I've done:

1. Add 'repo' scope to authentication, otherwise the repo list will be empty
2. Changing the URL for fetching repos for the organisation
3. Adding a "-b, --blacklist [repos]" option for simple repository blackling by name

The blacklist could be improved upon by allowing wild cards.