Bug 536457 - Include the version when pinging

Append a v=<version> to include the version and make it easier to add things in the future.

services/sync/modules/service.js

@@ -1104,7 +1104,7 @@ WeaveSvc.prototype = {
     let now = Math.floor(Date.now() / 1000);
     let lastPing = Svc.Prefs.get("lastPing", 0);
     if (now - lastPing > 86400) { // 60 * 60 * 24
-      infoURL += "?";
+      infoURL += "?v=" + WEAVE_VERSION;
       Svc.Prefs.set("lastPing", now);
     }