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