API v2

Trading APIs implemented in Grape, most code can be found in https://github.com/peatio/peatio/tree/api_v2/app/api/api_v2.

* Private APIs require authentication via signature, passed in as request params: https://github.com/peatio/peatio/blob/api_v2/app/api/api_v2/auth/authenticator.rb

* APIv2::Mount is the entry point:
https://github.com/peatio/peatio/blob/api_v2/app/api/api_v2/mount.rb

* Throttle is done with Rack::Attack: https://github.com/peatio/peatio/blob/api_v2/app/api/api_v2/constraints.rb

* Errors are defined at https://github.com/peatio/peatio/blob/api_v2/app/api/api_v2/errors.rb. 

* Swagger compliant documentation can be found at `/documents/api_v2` once rails server started.