Add a config initializer

Adds a middleware that populates req and res with the app config
Correctly resolve path for config file
Initialize config
Handle missing config files correctly
Empty test app config to run tests
Control feature visibility using flags in app config (DPSIR in this
case)
Default development config
Don't commit production configuration
README docs for app config files
Correct link to config README
Default feature config for test environment
App config can be retrieved without middleware
Correct americani(z|s)ation
Better error message
Remove indentation from deleted if block
Merge pull request #250 from unepwcmc/config

App Config File