Merge pull request #410 from beniz/ddg_url_encoding_utf8

ddg encoding of URLs to UTF-8

searx/engines/duckduckgo.py

         # append result
         results.append({'title': title,
                         'content': content,
-                        'url': res_url})
+                        'url': res_url.encode('utf8')})
 
     # return results
     return results