Move country specific code into their own apps.
Allow import of shapefiles with empty features.

If a feature lacks a geometry, cope with this and import the feature instead of
dying trying to access the non-existent geometry. Fixes #131.
Include query parameters in link to JSON.

Fixes #132.
Use view names rather than URLs in postcode view.

Test for correct display of UK partial postcode.
Merge branch 'issues/132-json-links'