Add blacklisted associations on Ember Blueprints

In case someone wants to blacklist an association to be returned in the
JSON for Ember-Data, you can specify it on the configuration.
Example:

User -> Auth
User -> Jwt

By NO MEANS the API should return the Auth data and Jwt tokens. This can
now be blacklisted and will never show up in the JSON.
Add blacklisted associations for User model
Add CORS config for localhost