Fix signature bug for twitter share (fix #17)

    Non-alphanum characters resulted into a truncated tweet

srv.js

@@ -95,7 +95,7 @@ function buildUrl(req) {
 function tweetMessage(req) {
   let _ = req.i18n._;
 
-  return (req.args.signature ? _('Faites comme ') + req.args.signature + ', s' : 'S')
+  return (req.args.signature ? _('Faites comme ') + encodeURIComponent(req.args.signature) + ', s' : 'S')
     + _('outenez ')
     + encodeURIComponent('La Quadrature du Net ! #LQDoN ')
     + encodeURIComponent(req.protocol + "://" + req.headers.host)