Adds a WDPA service class for importing protected areas

The class takes an array of PA attribute objects and imports them as
ProtectedAreas. The use of `.each` internally means that you can pass in
any lazy loaded database objects, like ARel or Sequel queries.
Introduces a geometry importer module

We cannot import geometries as attributes on ProtectedArea models as the
postgis adapter is not-performant when used this way for large geoms.
Instead, the geometry importer module is used to insert the geometries
directly on to the protected area, bypassing the postgis adapter.