fix https://github.com/Daplie/letsencrypt-cli/issues/20, use corret error object e instead of err

lib/get-acme-urls.js

@@ -30,8 +30,10 @@ module.exports.create = function (deps) {
         try {
           data = JSON.parse(data);
         } catch(e) {
-          err.raw = data;
+          e.raw = data;
-          err.stack += '\n' + data;
+          e.url = acmeDiscoveryUrl;
+          e.stack += '\n\nresponse data:\n'
+            + data + '\n\nacmeDiscoveryUrl:' + acmeDiscoveryUrl;
           cb(e);
           return;
         }