Implement natural language API #2027
Description
- https://cloud.google.com/natural-language/docs/
- https://developers.google.com/apis-explorer/#p/language/v1beta1/
/v1beta1/documents:analyzeEntities/v1beta1/documents:analyzeSentiment/v1beta1/documents:annotateText- Protobufs not released as of https://github.com/googleapis/googleapis/tree/6d6a1529e2c76db85b80c73760ed1791908f3cf2