Allow passing http options to all requests

[petomalina]

This will allow adding more options into each request. These options will be then merged by the angular http implementation together with the default options provided by the generator.

Sample implementation:

class APIService {
  readUsers(arguments ..., options): Observable<User[]> {
    return http.get('/users', options)
  }
}

The specification can be found here https://angular.io/guide/http#configuring-other-parts-of-the-request