Added the PATCH and HEAD methods to Request

Hi,

I'm currently patching the Request class with the following code to be able to use the PATCH and HEAD methods like other methods, such as `get()` or `put()`.

```js
var methods = {}

	Array.each(['head', 'HEAD', 'patch', 'PATCH'], function(method) {

		methods[method] = function(data) {

			var object = { method: method }

			if (data != null) object.data = data

			return this.send(object)
		}
	})

	Request.implement(methods)
```

It could save some bytes if they were defined in the core :)
I'd drop the caps.