Map pan animation jumps when adding a new page

[toolness]

This issue has been migrated from mozilla/webmaker-android#1701.

It was originally written by flukeout on Fri May 08 2015 and had the following description:

When adding a new page by tapping a Plus tile, the map pan jumps a bit before finishing the animation that puts the new page closer to the center of the viewport. The animation should pan the map over smoothly.

I think this i best observed when you're zoomed in to about the 3-up view.