[Feature] Support for OAuth

[EdricChan03]

There's currently no support for certain API options as of now due to a lack of OAuth capabilities.

TODO

• Decide on whether to leave this up to the consumer EDIT: This has to be left up to the consumer as the OAuth screen cannot be used with CORS
• Read up docs on how to implement OAuth
• Read up on how to use HttpClient with OAuth EDIT: Use the Authorization: Bearer HTTP header or the access_token parameter

Progress

5/10/18

I've added basic OAuth 2.0 support to the demo app, although I haven't committed the changes yet.

6/10/18

I'm planning to try to get this in by today.

New changes

There'll be several new parameters as part of OAuth to be implemented in NgxYtdApiGenericProperties:

Property	Description
accessToken	The access token returned from a successful authentication via Google's OAuth