The post can't be saved now unless it has a title and content.

Fixes [this issue](https://github.com/wordpress-mobile/WordPress-iOS-Editor/issues/441).

/cc @bummytime  
The reason I think it belongs into the post is that the VC shouldn't be checking for this at all - meaning the post either has unsaved changes, or not, regardless of previous attempts to save the changes.  The VC shouldn't have to worry about failed uploads at all.

The question that comes up to me is: how would a post not have changes, but still have failed to upload the latest changes.  Let me know your thoughts on this to move ahead.