closes#812
- replace defaults with consistently named .png files
- change the settings saving code so that it doesn't double-save images and save the defaults to the db
closes#276
- settings screen now loads a model when a pane is requested, rather than when the whole screen is requested
- added browse, read and edit methods and routes for users to the API
- added user model & template to client and wired everything up.
- provided default images for cover and profile picture