chore(hook): allow also to hook without adding any extension

Author: wzrdtales

lib/migration.js

@@ -37,7 +37,7 @@ var Migration = Skeleton.extend({
 Migration.registerHook = function(plugin, internals) {
 
   var plugin = plugin.hook('migrator:migration:hook:require');
-  internals.parser = internals.parse || {
+  internals.parser = internals.parser || {
     filesRegEx: filesRegEx,
     extensions: 'js'
   };
@@ -52,8 +52,9 @@ Migration.registerHook = function(plugin, internals) {
   })
   .each(function(parser) {
 
-    internals.parser.extensions = internals.parser.extensions + '|' +
-      parser.extensions;
+    if(parser && parser.extensions)
+      internals.parser.extensions = internals.parser.extensions + '|' +
+        parser.extensions;
   })
   .then(function() {
     internals.parser.filesRegEx = new RegExp(