Change Buffer.toString to conform to CommonJS Binary/F

Also add Buffer.inspect

lib/buffer.js

@@ -7,7 +7,7 @@ function toHex (n) {
   return n.toString(16);
 }
 
-Buffer.prototype.toString = function () {
+Buffer.prototype.inspect = function () {
   var s = "<Buffer ";
   for (var i = 0; i < this.length; i++) {
     s += toHex(this[i]);
@@ -17,8 +17,20 @@ Buffer.prototype.toString = function () {
   return s;
 };
 
-Buffer.prototype.toJSON = function () {
+Buffer.prototype.toString = function (encoding, start, stop) {
-  return this.utf8Slice(0, this.length);
+  encoding = encoding || 'utf8';
+  if (!start) start = 0;
+  if (!stop) stop = this.length;
+
+  if (encoding == 'utf8') {
+    return this.utf8Slice(start, stop);
+  } else if (encoding == 'ascii') {
+    return this.asciiSlice(start, stop);
+  } else if (encoding == 'binary') {
+    return this.binarySlice(start, stop);
+  } else {
+    throw new Error('Unknown encoding');
+  }
 };