Codeblock: Output source even if 'pygments_prefix' or 'pygments_suffix' is nil. Fixes #182

plugins/code_block.rb

@@ -90,6 +90,7 @@ module Jekyll
       source = safe_wrap(source)
       source = context['pygments_prefix'] + source if context['pygments_prefix']
       source = source + context['pygments_suffix'] if context['pygments_suffix']
+      source
     end
   end
 end