Create post

**Do not merge yet...**

Starting to wire up the beginnings of the create post process.
Added an event handler when the create post form is submitted. I'm using backbone.syphon to pull data out of the form and serialize it in a form we can use for models. I'm not doing any handling of exceptions yet
so all saves will fail.

We need to start handling custom forms in this feature.. I think that

* [x] Grab data form form and save to model
* [x] Add switching js for media/location/etc panes
* [x] Add frontend validation
* [ ] Handle server validation errors
* [x] Display custom form fields
* [x] Validate custom fields
* [x] Populate category selector with real categories
* [x] Match 'media bar' tabs to form groups
* [ ] Custom category selector
* [x] Remove hard coded form id
* [ ] ~~Add location name to point / geometry types~~ #123
* [ ] ~~hasLocation, hasMedia, etc functions on FormModel to allow checking which panes we show~~
* [ ] ~~Extend form group api: add 'key' and 'icon'~~ Now on now on #124
* Extend form attribute api
  * [ ] ~~Add placeholder~~ Now on #123 
  * [ ] ~~Find some way to pass extra config to form inputs~~ Now on #123

For this iteration I'm going to reduce to: main form, location and photo panes.
We won't really be handling video and audio uploads anyway - too complicated - but need to think about how we handling embeds in future.

Maybe we can mirror Crowdmap by just puling embed URLs out of the text.. we might still need to handle custom fields for video, audio, link inputs.. but can push that out a little later.



<!---
@huboard:{"order":7.5}
-->