allow protected keys to be set/unset + config_db tests

config/environments/test.rb

@@ -7,6 +7,9 @@ Foodsoft::Application.configure do
   # and recreated between test runs. Don't rely on the data there!
   config.cache_classes = true
 
+  # We clear the cache for each test, let's do that in memory.
+  config.cache_store = :memory_store
+
   # Do not eager load code on boot. This avoids loading your whole application
   # just for the purpose of running a single test. If you are using a tool that
   # preloads Rails for running tests, you may have to set it to true.