* new model `LocationType`
* fixed natural_key issue in AdministrativeArea/AdministrativeAreaType
adding more test data in fixture
fix the natural of location by including the parent area
add test of new natural key for location
fix/update docstring
pep compliancy with variable names
comment in tests: one-liner
add uniqueness together for location name in the same area
test uniqueness of location within an area
fix test. add intregrity/uniqueness tests
add uuidfield requirement
add uuid fields in: location, administrativearea, country
updating json data with uuid
using uuid to build/get natural in models. adding tests
remove obsolete comments
fix missing uuid field in test fixture
preventing uuid field to be blank/null. adding LocationTypeManager. removing unnecessary 'natural_key.dependencies'
cleaning unused method getting unexisting attribute
fix natural_key to return tuple
fix tests tu use tupled natural_key