Add Ember App Kit files

- Remove Backbone
- Add default ember app kit files in client/app
- Implement Login/Register in Ember
Add user login and password reset

- Add user initializer and push down current user
- Implement login on client side
- Add node-mailer for sending password reset emails
- Clean up unused files
Add configuration management

- Load config through config module (yaml)
- Add database and site config to default configuration
Fix feedback message styling on forms
Update README with configuration defaults