`routes` methods should interact with API GW directly, not through web actions

This client library currents copies the the CLI tool in interacting with the API GW service through [web action proxies](https://github.com/apache/incubator-openwhisk/tree/master/core/routemgmt), rather than interfacing with the [APIGW API](https://github.com/apache/incubator-openwhisk-apigateway/blob/master/doc/v2/management_interface_v2.md).

Migrating the implementation to talk directly to the APIGW is a better option. This will provide greater flexibility for the client library and stops using undocumented web actions.