Add key-change URL support

Fixes warning when retrieving LE URLs on staging or prod

lib/get-acme-urls.js

@@ -39,7 +39,7 @@ module.exports.create = function (deps) {
         }
       }
 
-      if (4 !== Object.keys(data).length) {
+      if (5 !== Object.keys(data).length) {
         console.warn("This Let's Encrypt / ACME server has been updated with urls that this client doesn't understand");
         console.warn(data);
       }
@@ -56,6 +56,7 @@ module.exports.create = function (deps) {
       , newCert: data['new-cert']
       , newReg: data['new-reg']
       , revokeCert: data['revoke-cert']
+      , keyChange: data['key-change']
       });
     });
   }

node.js

@@ -9,7 +9,7 @@ var defaults = {
   productionServerUrl:    'https://acme-v01.api.letsencrypt.org/directory'
 , stagingServerUrl:       'https://acme-staging.api.letsencrypt.org/directory'
 , acmeChallengePrefix:    '/.well-known/acme-challenge/'
-, knownEndpoints:         [ 'new-authz', 'new-cert', 'new-reg', 'revoke-cert' ]
+, knownEndpoints:         [ 'new-authz', 'new-cert', 'new-reg', 'revoke-cert', 'key-change' ]
 , challengeType:          'http-01'
 , rsaKeySize:             2048
 };