Set the default value of metadata as empty hash string in both Rails …

…4 and 5

Use String#dump because String#inspect is just for debugging

lib/generators/statesman/generator_helpers.rb

@@ -46,7 +46,7 @@ def database_supports_partial_indexes?
     end
 
     def metadata_default_value
-      Utils.rails_5_or_higher? ? "{}" : "{}".inspect
+      "{}".dump
     end
   end
 end