Set the allow_editing wiki option to true by default.

lib/gollum/app.rb

@@ -102,7 +102,8 @@ module Precious
       @css = settings.wiki_options[:css]
       @js  = settings.wiki_options[:js]
       @mathjax_config = settings.wiki_options[:mathjax_config]
-      @allow_editing = settings.wiki_options.fetch(:allow_editing, true)
+      settings.wiki_options[:allow_editing] = settings.wiki_options.fetch(:allow_editing, true)
+      @allow_editing = settings.wiki_options[:allow_editing]
     end
 
     get '/' do

lib/gollum/helpers.rb

@@ -39,7 +39,7 @@ module Precious
       url.gsub('%2F', '/').gsub(/^\/+/, '').gsub('//', '/')
     end
 
-    def forbid(msg = "Forbidden.")
+    def forbid(msg = "Forbidden. This wiki is set to no-edit mode.")
       @message = msg
       status 403
       halt mustache :error