Add rate limiting information to client responses

[mboylevt]

This PR surfaces our rate limiting headers from both of our RL sources - cloudflare and shapeways.com

[coveralls]

Coverage decreased (-4.5%) to 74.392% when pulling d3dc8c7 on mb-RateLimit into 4b82082 on master.

[grimzy]

Tiny recommendation to slightly reduce code complexity would be to remove unnecessary elses:

(untested)

# Handle HTTP errors
if response.status_code != HTTP_OK:
    # Generic error
    content = response.json()
    content[CONTENT_SUCCESS] = False
    content[CONTENT_RATE_LIMIT] = rate_limit.__dict__

    if response.status_code == HTTP_RATE_LIMITED:
        # We're rate limited
        rate_limit.is_rate_limited=True

        # Shapeways Rate limiting - stupidly, we move the retryInSeconds entry from the response headers
        # to the body.  Dealing with this here.
        rate_limit.rate_limit_remaining = 0
        rate_limit.rate_limit_retry_inseconds = response.json()['rateLimit']['retryInSeconds']

        if CF_RATE_LIMIT_RETRY in headers.keys():
            # Limited by CF - backoff for a number of seconds
            rate_limit.rate_limit_type=CF_RATE_LIMIT
            rate_limit.rate_limit_retry_inseconds=headers[CF_RATE_LIMIT_RETRY]

        content = {CONTENT_SUCCESS: False, CONTENT_RATE_LIMIT: rate_limit.__dict__}
        
    return content

[grimzy]

Not required change => ✅

[mboylevt]

So i had that originally - trouble is that the json payload only has the rateLimitRetry key if and only if the rate limiter has been achieved. Therefore, this statement cannot be treated as always valid

rate_limit.rate_limit_retry_inseconds = response.json()['rateLimit']['retryInSeconds']

Hence, extra elses