If rate limiting information hasn't been retrieved already, it will be checked
rather than just assuming 5000 requests remaining of 5000.
Add an additional attribute `rate_limiting_resettime` to reflect github's new
X-RateLimit-Reset header. This integer value is a unix timestamp.
RateLimiting unit test updated accordingly.
This is a minor thing. It’s a convention, not a rule (obviously)—but it’s also a best practice.
Many text editors look for this kind of comment as the first line—or second line, if there is a shebang (the `#!/usr/bin/env python`, or whatever else)—and make use of this to determine the file’s encoding.
Ed Jackson