Add a way to create feedback

[rfay]

Feedback is really working well on WS, but would be great if giving feedback could be incorporated into the app. See https://github.com/warmshowers/Warmshowers.org/wiki/Warmshowers-RESTful-Services-for-Mobile-Apps#wiki-create_feedback

[rfay]

This is super important - still hoping to have feedback-creation capability in the app as a high priority. Feedback is the thing that makes the community work.

[RajanFernandez]

Hey, I have made some view controllers for creating feedback but I'm a bit new to iOS development and am stuck on how to successfully submit the feedback via the restful service. I've noticed that the post parameters for the 'create feedback' service are quite different from the other services. Are these post parameters here also simply dictionary keys?? e.g. 'node[type]'