Add buffer support

[terribleplan]

It would be nice if buffers were natively supported to enable the following pattern:

var fs = require('fs'),
    stripCssComments = require('strip-css-comments');

fs.readFile('./file.css', function(err,buf){
    console.log(stripCssComments(buf));
});

which is quite natural to use in node.

Worst case you could just turn buffers to strings with .toString()

[sindresorhus]

Yup, I wanted to support that, but would prefer to strip out the comments without even having to convert it to a string. Would probably be faster too #1.

[kevva]

How would you do that? Checking for the comment bytes and just removing them that way?

[sindresorhus]

I think so.

[sindresorhus]

Alright, so turns out buffers are actually slower than strings for this in latest Node.

See #9

So going with just converting the Buffer to a string for now...