manually specify encoding

lib/get-acme-urls.js

@@ -17,6 +17,7 @@ module.exports.create = function (deps) {
     // TODO check response header on request for cache time
     return request({
       url: acmeDiscoveryUrl
+    , encoding: 'utf8'
     }, function (err, resp) {
       if (err) {
         cb(err);