initial tests for /taxonomy/country with stubs so they fail properly
json of all countries from world bank api

The World Bank: Country Queries: http://api.worldbank.org/countries?format=json&per_page=300
implement loading from fixtures to mongodb

I also cleaned up some of the mongodb integration, graviton now only
uses the default database in mongodb per default.
refactor routing loader
boilerplating for country resource
set content-type in listener
fix schema tests
content-type header generation based on route name
fix tests

Some small differences with the original data as well as not going down the
float precision rabbit hole for now.
implemet basic /taxonomy/country resources