default to generation 0

libs/strophe/strophe.jingle.sdp.util.js

         candidate.port = elems[5];
         // elems[6] => "typ"
         candidate.type = elems[7];
+
+        candidate.generation = '0'; // default, may be overwritten below
         for (i = 8; i < elems.length; i += 2) {
             switch (elems[i]) {
                 case 'raddr':