Sort published posts with local edits to the top

[vickychijwani]

This is to address a UX issue when editing published posts: the user may forget to publish their changes if the post is lost in a huge list. The current behaviour is:

• For drafts, changes are auto-uploaded to the server on tapping the back button.
• For published posts, on tapping the back button, changes are saved locally on the device until the user explicitly updates the post by tapping the "Update" button in the post editor. The user is informed of this behaviour on the post list, which changes the status to "Changes auto-saved, not published yet". The reason it works this way is because it is unsafe to assume that the user would always want to publish their changes - a "back" action can be interpreted as a cancel too.