Ember editor save and publish button functionality

Closes #2747
- Added new 'editor-save-button' view and template.
- Added save action to post controller.
- Set a new post as the default model for the /editor/ route.
- Set the `posts/post` controller as the controller for the /editor/
  route.
- Needs ghost-popover #2418 component for full pop-up functionality
Add active class to settings tabs

Closes #2751
Fix default user cover on settings pane

Closes #2806
- Ensures that the user's cover property is a string, otherwise uses the
  default cover.
Update ember post fixture data.

closes #2803
- corrected status published string
- corrected page to not use invalid choices
- updated id integer to start at 1 and not 0
- updated to repeat 31, added a note about removing post id:0
Merge pull request #2810 from shindakun/fixtureupdate

Update ember post fixture data.
Merge pull request #2804 from novaugust/ember-settings-currently-active-pane

Add active class to settings tabs
Merge pull request #2786 from novaugust/ember-editor-save-and-publish

Ember editor save and publish button functionality
Merge pull request #2807 from novaugust/ember-user-cover-default

Fix default user cover on ember settings pane
Refactore slug API for generating tag and post slugs.

Closes #2601
- Removed slug generation from the post API
- Added new, self-contained slug API
- Fixed slug permissions in the fixtures files
- Added a HTTP route for the new API method
- Added integrational tests
Fix up url helper unit tests

Closes #2817
-use async semantics for tests
-fix api.settings.read stub for the url helper describe block
-rename test to describe actual behavior (return '/' instead of '')
Fix 403 errors after signup

Closes #2819

- Keep around the _csrfSecret on the session after regenerating
Merge pull request #2818 from jaswilli/issue-2817

Fix up url helper unit tests
Merge pull request #2814 from lennerd/issue-2601

Refactore slug API for generating tag and post slugs
Clean up routes. Use new slug endpoint in admin.

refs #2814
-removed route /posts/slug/:title due to API change
-changed admin to use new slug endpoint
-removed duplicate notifications routes
Update Ember Components with proper gh- prefix

GH-ISSUE 2373
Ember Data with Posts

Ref #2699

- Introduce ember data dependency
- Add loadInitializers and refactor most initializers into one combined
- Add Post ember data model
- Refactor generateSlug to use title of post and ghostPaths
- Refactor post controller to not reference model.property everywhere
- Use RESTAdapter for posts, users and tags
- Setup author and tag relations in Post model
- Fix broken API calls by adding CSRF header
- Add initiaizer for csrf value
- Use actual User model for current user initializer
- Add action for setting featured post, test with actual api call
- Fix the sending of UUID's up to the server
- Refactor current-user to use ember-data store
- If a user is preloaded in the application, use pushPayload to put it
in the store
- Do a lookup on the store to get an actual User model for injection
- Fix posts/post controllerName in route/new.js
- Alter signup process to push user into ember data store
Merge pull request #2826 from jaswilli/route-cleanup

Clean up routes. Use new slug endpoint in admin.
Merge pull request #2718 from jgable/emberData

Ember Data with Posts
Merge pull request #2828 from lholmquist/GH-2373

Update Ember Components with proper gh- prefix
Merge pull request #2820 from jgable/fix403

Fix 403 errors after signup