Stats pages

This pull request adds the Stats pages:

Global:
/stats/global

Regional
/stats/regional/[:iso]

Country
/stats/country/[:iso]

Adds 3 controllers (one for each stat type) in the /app/controllers/stats foder.

It also creates an integration test and controllers tests for the features above.

Still work to do on CSS and and the views may be refactored.

Geospatial stats are not available so they are commented in the controllers and not present in the views
The  problem here is that we don't have a global/regional/national dataset to set the bounds. Should Iimport geometries or dhould we set them in other way?