Use iter_user_repos where appropriate
If the branch does not exist, no GitHub error will be thrown.  We need to check if the response is None.
Fetch pull requests for easy cherry-picking
Don't bomb out if issues aren't enabled
Another GitHubError that no longer exists
Python 3 compatibility: replace 0777 with 0o777
Add git-hub calendar: a calendar display like on your profile page
Docs/installer updates
calendar: underline the first day of each month
Regex assumes that .git extensions will always exist, but doing a git clone will leave it out.

Make regex .git check to be optional.