Correct errors introduced in 4f5536dcfc124511987d2e4d9ffcd4005e99193d
Add tests and config option to turn off caching

This commit adds tests to verify the proper functioning of the caching
service's `_data` method, cleans up some tests, and adds a configuration
option to the application to disable caching entirely.
Normalize test urls
Merge pull request #45 from natgeo/feature/MIE-1493

Correct errors introduced in 4f5536dcfc124511987d2e4d9ffcd4005e99193d