Move schemas to separate module

Use front end URI instead of API

Fix connection class imports

License information

Move redirect uri generation to getRedirectUri function of Connection class. ...

Use api_endpointPublic instead of cdn_endpointPublic

Refreshable connections, refactoring, access-token endpoint ...

- Aded /users/@me/connections/:connection_name/:connection_id/access-token
- Replaced `access_token` property on ConnectedAccount with `token_data` object for refreshing tokens
- Made a common interface for connection things like ComonOAuthTokenResponse
- Added `RefreshableConnection` class
- Added token refresh to Spotify connection (disabled)

`handleCallback` returns connection if created for `USER_CONNECTIONS_UPDATE`

adding connection now works

add connections