User content persist - fixes 82

see #82 

- adds UserContent model with validation
- adds postUserContent method to api module
- when the buttons are clicked, sends the request to the api (refer to https://github.com/codeforamerica/bestnest-api/pull/65)

![](http://media.giphy.com/media/u6M4FX3PFiDPG/giphy.gif)