Implement Notifications for Ember

closes #2417
- Adds Notification(s)Component
- Render notifications in application.hbs
- Adds handleError in application route
Set user profile website field to type url

closes #2588
Merge pull request #2590 from jaswilli/ember-userprofile

Set user profile website field to type url
Merge pull request #2472 from halfdan/ember-notifications-2417

[Ember.js] Implement Notifications for Ember
[wip] Ember settings/general

- 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
Trying to fix casper module ref
Fixing JSHint errors
Attempt 3 at fixing casper ref
- Let ApplicationRoute handleValidationErrors
Fix actions hash in controller and use bind-attr
Changes based on review notes

- Refactor to use single SettingsModel
- Implement description word count
- Fix broken ajax reference by actually importing ajax method