Enable threadsafe mode for all environments.

It's a better way to test.
Add NCS Navigator configuration to application object.
GET /api/v1/event_types scenarios.

This commit also introduces PUT /api/v1/mdes_version, which so far is
really only being used for testing.  I may get rid of it in a future
commit.
Implement GET /api/v1/event_types.
Remove ActiveRecord-specific bits from RSpec harness.