Map view shifts after returning to it from the Project Settings view

This issue has been migrated from mozilla/webmaker-android#1988.

It was originally written by flukeout on Thu May 21 2015 and had the following description:

Steps to reproduce

• In a new project, zoom in a bit
• Move the map a bit so that no tiles are perfectly centered on the view
• Enter the Project Settings view
• Tap the back arrow to return to the map view
• When the map view shows, moves to center on one of the tiles

It should just stay where it was when you left the map view.

Note: This happens when you delete a tile on the edge of a project.