Do not include url and author_id in post payload.
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.

JohnONolan/Ghost-Admin,TryGhost/Ghost-Admin,TryGhost/Ghost-Admin,acburdine/Ghost-Admin,JohnONolan/Ghost-Admin,acburdine/Ghost-Admin,airycanon/Ghost-Admin,kevinansfield/Ghost-Admin,kevinansfield/Ghost-Admin,airycanon/Ghost-Admin,dbalders/Ghost-Admin,dbalders/Ghost-Admin