Update to Ember 1.9.0.

No Issue
- Ember@1.9.0
- Handlebars@2.0.0
- grunt-ember-templates@0.5.0-alpha
allow re-login when authorization fails on editor.edit route
Fixup behavior and styling of editor re-auth.

Closes #2092
- Adds styling for re-auth modal.
- Prevent transition to posts route on success.
- Clear credentials from controller.
- Handle confirmAccept action if form is submitted via 'enter'.
- Only allow re-auth as the user that was previously logged in.
Merge pull request #4602 from jaswilli/better-auth-retry

Allow re-authentication in editor after 401 response
Do not include url and author_id in post payload.

No Issue.
- Neither of these properties should be included in the
  payload sent from the client to the API.  URL is a
  read-only virtual property, and author_id is inserted
  locally as a convenience.
Remove files for a modal that is no longer used.

Refs #4602
- The modal dialog that used to be shown when re-auth was
  needed in the editor has been replaced.
Merge pull request #4655 from jaswilli/modal-cleanup

Remove files for a modal that is no longer used.
Merge pull request #4653 from jaswilli/client-data

Do not include url and author_id in post payload.
Version bump to 0.5.7
Prevent publish-bar from floating up
Merge pull request #4526 from knownasilya/patch-1

Prevent publish-bar from floating up on mobile
stop middleware converting favicon to string

closes #4658

- adds conditional to prevent favicon being processed as a string
Merge pull request #4661 from cobbspur/favicon

stop middleware converting favicon to string
Merge pull request #4620 from jaswilli/ember19

Update to Ember 1.9.0.
Tag Management: Delete Flow

Closes #4633
- The ‘delete’ button is now a smaller plain text link, opening a
confirmation modal analog to the delete user/post flow
- Adding a post count is dependent on #4654, but the modal is already a
neat step up from the immediate, warning-less deletion.
Merge pull request #4656 from felixrieseberg/iss4633

Tag Management: Delete Flow
Navigation UI Mockup

Refs #4537

Static mockup of the navigation UI

- Includes hacky JS to simulate interactions (but not dragging, which is #4540 and no modal when deleting)
- Delete & add icons have invisible padding to increase hit area
- Drag handle has the `move` cursor
- Switches into a single column at 600px and below
Merge pull request #4665 from PaulAdamDavis/navigation-ui

Navigation UI Mockup