Auto-save changes

Refs #4259
- Auto-save new post when title loses focus.
- If a post has '(Untitled)' for a title, regenerate slugs
  on all title changes--same behavior as a new post that does
  not yet have a slug.
- Adjust some functional tests to handle the automatic transition
  from editor/new to editor/editor and the URL changes that go
  along with it.
More autosave improvements

issue #4305, issue #4259, issue #1413

- change new->edit transitionToRoute to be replaceRoute
- auto focus in the editor on transition to the edit route
- change the one-time autosave to happen on codemirror focusin instead of title focusout
- re-add removed tests, and reorder broken test
Merge pull request #4307 from ErisDS/pr-4305

An update to PR 4305
Upgrading Casper to 1.1.1
Merge pull request #1 from TryGhost/master

resyncing upstream