typo fix

lib/core.js

@@ -204,7 +204,7 @@ function getCertificateAsync(account, args, defaults, handlers) {
   });
 }
 
-function getOrCreateDomainCertificate(account, args, defaults, hanlers) {
+function getOrCreateDomainCertificate(account, args, defaults, handlers) {
   return fetchFromConfigLiveDir(args).then(function (certs) {
     // if nothing, register and save
     // if something, check date (don't register unless 30+ days)