[WIP] Ember settings/general

Ref #2421

- Settings fixture that doesn't seem to work
- SettingsGeneralRoute with model function calling api
- SettingsGeneralModel with save method stubbed
- SettingsGeneralController with actions for save, uploadLogo and uploadCover

Wanted to get some review on the model save method I have here.  Seems odd to have to write this stuff by hand and all the guides say we should be using either ember-data or ember-model.

TLDR; I need an adult to take a look.