Rebase and fix failing tests in mkdirp

src/shell.js

@@ -365,7 +365,7 @@ define(function(require) {
     callback = callback || function(){};
 
     if(!path) {
-      callback(new Errors.EInvalid());
+      callback(new Errors.EINVAL('missing path argument'));
       return;
     }
     else if (path === '/'){
@@ -413,7 +413,7 @@ define(function(require) {
         }
         //not a directory
         else if (stat.type === 'FILE') {
-          callback(new Errors.ENotDirectory());
+          callback(new Errors.ENOTDIR());
           return;
         }
       });