update throttling

[willpote]

Changing ip rate limiting to be per endpoint, and dropping numbers especially for post order:

Previously we allowed 4 TPS across all endpoints, so this actually allows a higher TPS in aggregate, but puts more restrictions on POST order

Let me know if we feel this is too low for anything:

POST order: 100 per 5 mins, i.e. 1 every 3 seconds
GET orders: 900 per 5 mins, i.e. 3 TPS
GET nonce: 150 per 5 mins, i.e. 1 every 2 seconds
GET docs: 100 per 5 mins, i.e. 1 every 3 seconds

Also the first rule, which is first priority, allows requests with api key through with no throttle

[rileydcampbell]

The only one I'd change is the get orders bc we bumped that specifically for market makers who asked to be able to query more frequently during burst testing.

althought I guess 3 tps is still pretty reasonable considering there's only a block every 12 secs.