- All definitions have been replaced by classes:
http://graphql-ruby.org/schema/class_based_api.html
- Authorization & Presentation have been refactored to work in the
class based system
- Loaders have been replaced by resolvers
- Times are now coersed as ISO 8601
By specifying a presenter for the object type, we can keep the logic
out of `GitlabSchema`.
The presenter gets initialized using the object being presented, and
the context (including the `current_user`).
