Dynamic rate limiting

[mattbdean]

The default rate limiter should be able to use the special response headers to dynamically adjust the request rate, just like in v0.9.0

• X-Ratelimit-Used: Approximate number of requests used in this period
• X-Ratelimit-Remaining: Approximate number of requests left to use
• X-Ratelimit-Reset: Approximate number of seconds to end of period

[ioggstream]

See the new ratelimit standardization proposal.

The proposal was:

• recently presented at the HTTP Workgroup during the IETF Meeting
• implemented by Kong
• under implementation in 3scale

it uses

X-Ratelimit-Limit: Maximum number of requests allowed
X-Ratelimit-Remaining: Approximate number of requests left to use
X-Ratelimit-Reset: Approximate number of seconds to end of period