Update client to respect the newer `RateLimit` header (#115)

* update test to target new header (currently failing)

* fix test

* bump version

Fix rate limiting backoff behavior (#113)

Fix responses with 204 status codes (#108)

* Don't try to json 204 responses and add test to make sure they succeed

* Bump version number

Add retries for addtional response codes (#106)

* Add retries for status code 503, and status codes 502 and 504 on GET requests. For 503s, requests can be retried after between 2-4 seconds, for 502 and 504s, we want a retry every 60-90 seconds, with that number increasing each time we retry

* Bump up version, even though 1.2 was never released

* Address review comments

* Adjust comment

* single quotes

Bump version to v1.1

version bump

bump version to v0.5

remove six from setup, bump version