Clean up Country stats library

As with prior commit -- move most of responsibility from Stats modules
to models. Most of the stats are to do with counting relations, etc. so
the relations are handled by the model, and the decision to count is
handled by the controller.
Refactor global stats
Refactors stats controller code in to presenters

Previously the stats controllers had quite a lot of say in how the stats
were presented (e.g. deciding whether or not to round the values, etc.).
This responsibility has moved to the `StatisticPresenter`.

StatisticPresenter proxies methods to the model or model statistic, and
presents the data differently depending on what was requested. For
example, the global pa coverage percentage is rounded to one significant
digit.
Update PA percentage test to reflect presenter
deletes temp tables on cartodb after inserting them on main table
removes 2 whitespaces
Merge pull request #90 from unepwcmc/cartodb-table-remover

deletes temp tables on cartodb after inserting them on main table
Merge pull request #89 from unepwcmc/stats-refactor

Stats display refactor
Moves model geometry methods in to a concern

Conflicts:
	app/models/protected_area.rb
Merge branch 'master' of github.com:unepwcmc/ProtectedPlanet

* 'master' of github.com:unepwcmc/ProtectedPlanet:
  removes 2 whitespaces
  deletes temp tables on cartodb after inserting them on main table
  Update PA percentage test to reflect presenter
  Refactors stats controller code in to presenters
  Refactor global stats
  Clean up Country stats library

Conflicts:
	app/models/country.rb
	app/models/region.rb
	test/models/country_test.rb
Merge branch 'master' into elastic-search

* master:
  Moves model geometry methods in to a concern
  removes 2 whitespaces
  deletes temp tables on cartodb after inserting them on main table
  Update PA percentage test to reflect presenter
  Refactors stats controller code in to presenters
  Refactor global stats
  Clean up Country stats library

Conflicts:
	app/models/country.rb
	app/models/protected_area.rb
	app/models/region.rb
	lib/modules/stats/global.rb
	test/models/country_test.rb
	test/models/protected_area_test.rb
	test/models/region_test.rb