Don't use PyPI mirrors now it's CDNd
Use GeoJSON rather than WKT for geography serialisation
Update URL rules to match Molly 1.x
Add Cucumber config

This means Cucumber can still find the appropriate support files when running a specific file in a nested directory.
Add step definitions for POI scenarios
Update README to make clear unofficial status of Molly-next

Also, update the Travis badge now this has been moved to an organisation, and give instructions on how to run Cucumber