def post(uri, body = nil, headers = {} )
      request :post, uri, body: body, headers: headers
    end
def post(uri, body = nil, headers = {} )
      request :post, uri, body: body, headers: headers
    end
Send a POST request.
 @param uri (see #get)
 @param body [Hash] a hash that will be JSON encoded for the body of this request.
 @param headers (see #get)
 @return (see #request)