[#882] Fix global maps

The global maps had some issues, that have been resolved:
- Global project map was zoomed out too much and showed pins outside of the map (-87, -87). Zoom level is now min 2 and points above 80 or below -80 (latitude) are filtered out.
- Global organisation map did not show any pins, due to the change in logos. This is now fixed.
- All pins at 0, 0 are now filtered out.
Merge pull request #883 from akvo/feature/882_v3_maps_fix

[#882] Fix global maps