Ignore more files and add staging database config.

.gitignore

@@ -27,6 +27,7 @@
 
 # Ignore master key for decrypting credentials and more.
 /config/master.key
+/config/credentials.yml.enc
 
 /public/packs
 /public/packs-test
@@ -107,3 +108,4 @@ yarn-debug.log*
 
 # Ignore IJ IDE directory
 /.idea/
+*.iml

config/database.yml

@@ -84,3 +84,7 @@ test:
 production:
   <<: *default
   url: <%= ENV['DATABASE_URL'] %>
+
+staging:
+  <<: *default
+  url: <%= ENV['DATABASE_URL'] %>