Add areas endpoint for specific area types.

Expose a subset of Mapit area data for specific types (EUR, CTY, DIS, LBO).
Merge pull request #86 from alphagov/expose_mapit_areas

Add areas endpoint for specific area types.
Search places by postcode.
Add some integration tests for places API.
Merge pull request #85 from alphagov/postcode_search

Postcode search
Add a way to handle differing responses
Add areas by postcode lookup
Expose area type field
Simplify and rename mapit api classes
Add integration tests for areas endpoints
Merge pull request #87 from alphagov/add_areas_for_postcode_lookup

Add areas for postcode lookup
Remove all traces of business support schemes