Array parameters support (#380)

* Array parameters support

* Shorter version of array syntax checking, no hasOwnProperty using

Author: nekrasoft

lib/incoming_form.js

@@ -84,7 +84,19 @@ IncomingForm.prototype.parse = function(req, cb) {
     var fields = {}, files = {};
     this
       .on('field', function(name, value) {
-        fields[name] = value;
+        if (name.slice(-2) === '[]') {
+          var realName = name.slice(0, name.length - 2);
+          if (realName in fields) {
+            if (!Array.isArray(fields[realName])) {
+              fields[realName] = [fields[realName]];
+            }
+          } else {
+            fields[realName] = [];
+          }
+          fields[realName].push(value);
+        } else {
+          fields[name] = value;
+        }
       })
       .on('file', function(name, file) {
         if (this.multiples) {