404 and return

Need the return to invoke the 404 response.
Move related items tests into their own spec file

There are now a number of tests for this feature, so it's probably
best to separate this out into another file.
Use the CONTENT_API_CREDENTIALS

There aren't any different credentials for app endpoint. Rather, it's
using an app-wide GDS API key.
404 and return
Provide some controller specs for countries#edit

Make sure some of the basic interactions we do work as expected
against the controller.

Most of these just check the response given that certain bits of data
are available.
Correctly provide a 404 when a country isn't found
If we're going to use LOTR references, use actual nations

"Middle Earth" is the fictional universe setting of LOTR. Properly,
Middle-earth is the central continent of the imagined world, not a
name of the entire world.

These are two actual nations from LOTR.
Hook up GDS API Panopticon test helpers to controller specs
PUT requests with the correct parameters will update country artefacts