Consistent use of string type for session_keys_to_persist

Author: grega

spec/dummy/config/initializers/rpi_auth.rb

@@ -6,7 +6,7 @@
   config.brand = 'codeclub'
   config.host_url = 'http://localhost:3009'
   config.identity_url = 'http://localhost:3002'
-  config.session_keys_to_persist = %w[foo bar]
+  config.session_keys_to_persist = 'foo bar'
   config.user_model = 'User'
 
   # Redurect to the next URL