Documentation and API questions

[RobK410]

Issue

The documentation is great, but there are a couple of missing pieces to help create a complete client wrapper for the API.

1. Models do not specify which parameters are required and which are optional. It would be great to document the models as well as API endpoints.
2. In Fundraisers, there is no detail on what the expected output from the GET and POST operations. For GET, would like a Fundraiser model.
3. Operations should have expected HTTP codes (e.g. 200 for a successful fundraiser, 402 for missing parameters).
4. Is there a sandbox option for creating a fundraiser and testing webhooks? It would be great to be able to test and get server feedback in a sandbox before going live.
5. Will there be PUT and DELETE options for Fundraisers in the future?
   Thank you!