Fix conditional check on git adapter for String extension library.

lib/gollum/app.rb

@@ -25,15 +25,15 @@ Gollum::set_git_max_filesize(190 * 10**6)
 
 # Use stringex #to_url only to leverage its #to_ascii method when using grit
 class String
-  if defined?(Gollum::GIT_ADAPTER) && Gollum::GIT_ADAPTER != 'grit'
+  if Gollum::GIT_ADAPTER != 'grit'
     def to_ascii
       self # Do not transliterate utf-8 url's unless using Grit
     end
-  end
 
     def to_url
       to_ascii
     end
+  end
 end
 
 # Run the frontend, based on Sinatra