Upgrade Leaflet to 0.7.2

Summary: Upgrading Leaflet to fix some bugs for D33

Test Plan:
- Check maps in UI still loading
- Check popups still work as expected
- Open create post dialog, check that location editors load
- Location editor: Check that locate button still works
- Location editor: Check the geolocation search still works

Reviewers: eyedol, shadowhand

Reviewed By: shadowhand

Differential Revision: https://phabricator.ushahidi.com/D42