Error modifying "author" attribute before post record has been created
Error modifying "author" attribute before post record has been created

fixes #3523
- when changing the author, added a check to NOT trigger a save if the post has not been created/saved as yet

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