Transition to editor.edit after saving a new post

Closes #2860
- `editor-base-controller`'s `save` action returns a promise with the model
  after saving
- `EditorNewController` will transition to `EditorEditController` upon a
  successful save (model has an id)
- Removed a console.log in editor's save function
Merge pull request #2930 from novaugust/save-new-post-transition

Add transition to editor/:id upon saving new post