remove unnecessary specification of encoding

Author: Jonathan Dahan

lib/multipart_parser.js

@@ -58,8 +58,8 @@ MultipartParser.stateToString = function(stateNumber) {
 
 MultipartParser.prototype.initWithBoundary = function(str) {
   this.boundary = new Buffer(str.length+4);
-  this.boundary.write('\r\n--', 0, 'ascii');
-  this.boundary.write(str, 4, 'ascii');
+  this.boundary.write('\r\n--', 0);
+  this.boundary.write(str, 4);
   this.lookbehind = new Buffer(this.boundary.length+8);
   this.state = S.START;