def put(uri, payload)
      headers = { 'Content-Type' => 'application/json' }
      res = Excon.put(@base_url + uri.to_s,
                      headers: headers,
                      user: username,
                      password: password,
                      ssl_verify_peer: false,
                      body: payload)
      api_response res
    end
def put(uri, payload)
      headers = { 'Content-Type' => 'application/json' }
      res = Excon.put(@base_url + uri.to_s,
                      headers: headers,
                      user: username,
                      password: password,
                      ssl_verify_peer: false,
                      body: payload)
      api_response res
    end
http request via put
 @param [string] uri
 @return [Object] ruby representation of the json response
                  if the reponse body  does not parse, raises
                  a SFRest::InvalidResponse