This works for both ServerResponse and ClientRequest.
Adds three new methods as a couple properties to to OutgoingMessage objects.
Tests by Charlie Robbins.

Change-Id: Ib6f3829798e8f11dd2b6136e61df254f1564807e

Needs more tests.

Thanks Sitelier. Closes GH-651.

See http://code.google.com/p/v8/issues/detail?id=884

This adds support for a cache object to be passed to the
fs.realpath and fs.realpathSync functions.  The Module loader keeps an
object around which caches the resulting realpaths that it looks up in
the process of loading modules.

This means that (at least as a result of loading modules) the same files
and folders are never lstat()ed more than once.  To reset the cache, set
require("module")._realpathCache to an empty object.  To disable the
caching behavior, set it to null.

Any array-ish thing (whether a Buffer, an Array, or just an object with
a numeric "length") is interpreted as a list of bytes.

This allows the various fs utilities and process.umask to be used in
ECMAScript 5 Strict Mode, where the octal literal format is verboten,
without requiring users to litter their code with a bunch of parseInt
calls.

Closes GH-644.

Closes GH-640.

This adds basic support for situations where there is a package.json
with a "main" field.  That "main" module is used as the code that is
loaded when the package folder is required.