Bring back Cookie token extractor

[daffl]

This pull request brings back parsing the JWT from the cookie. It will only be available if the cookieParser middleware has been registered (which we are not doing by default) and authentication cookies are enabled.

This change touches on many open issues, specifically in regards to using authentication for server side rendering and adding multiple accounts to the same user. Related issues:

• JWT Cookie authentication#389
• Allow to add multiple oAuth providers to a user authentication#550
• Associate multiple authentication strategies with 1 user authentication#402
• Update an existing entity in verifier authentication-oauth2#18
• attach social to current user authentication#626
• cookie reused from server in SSR app authentication#619
• No way to share token between socket-rest-express  authentication#607
• Express middleware not setCookie authentication#617
• Authentication with server-side rendering authentication#560
• Allow to add multiple oAuth providers to a user authentication#550
• A supposed way to auth requests from SSR to Feathers API authentication#469
• Associate multiple authentication strategies with 1 user authentication#402
• approach to link existing local accounts with oauth2 feathersjs/feathers#661
• Authentication feathersjs/feathers#574

[TimNZ]

@daffl Legend. Mapping out authentication flows for various signup/login scenarios using mixed auth is #1 job right now so will dig into this shortly and provide feedback.