to solve EISDIR error (node-formidable#424)

* to solve EISDIR error

to solve EISDIR error when trying to submit a form with no file
selected.

* del .ideal and modify incoming_form

remove needless .idea things and change the condition to !part.filename

* remove needless .idea

remove needless .idea

Author: lyyh3c

lib/incoming_form.js

@@ -182,7 +182,7 @@ IncomingForm.prototype.onPart = function(part) {
 IncomingForm.prototype.handlePart = function(part) {
   var self = this;
 
-  if (part.filename === undefined) {
+  if (!part.filename) {
     var value = ''
       , decoder = new StringDecoder(this.encoding);