TypeScript definitions

It would be nice to include typescript definitions. Something like this:

```typescript

declare module 'quip' {
import { IncomingMessage, ServerResponse } from 'http';

type StatusCode =
| 200
| 201
| 202
| 204
| 301
| 302
| 304
| 400
| 401
| 403
| 404
| 405
| 409
| 410
| 500;

type RedirectionCode = 301 | 302;

type ContentType =
| 'text/plain'
| 'text/html'
| 'application/xhtml+xml'
| 'text/css'
| 'text/xml'
| 'application/atom+xml'
| 'application/rss+xml'
| 'application/javascript'
| 'application/json';

interface QuipExtensions {
status(code: StatusCode): QuipResponse;
headers(headers: { [key: string]: string }): QuipResponse;
ok(): QuipResponseFunction;
created(): QuipResponseFunction;
accepted(): QuipResponseFunction;
noContent(): QuipResponse;
moved(loc: string): QuipResponse;
redirect(loc: string, code?: RedirectionCode): QuipResponse;
found(loc: string): QuipResponse;
notModified(): QuipResponse;
badRequest(): QuipResponseFunction;
unauthorized(): QuipResponseFunction;
forbidden(): QuipResponseFunction;
notFound(): QuipResponseFunction;
notAllowed(): QuipResponseFunction;
conflict(): QuipResponseFunction;
gone(): QuipResponseFunction;
error(): QuipResponseFunction;
text(data?: T): QuipResponse;
plain(data?: T): QuipResponse;
html(data?: T): QuipResponse;
xhtml(data?: T): QuipResponse;
css(data?: T): QuipResponse;
xml(data?: T): QuipResponse;
atom(data?: T): QuipResponse;
rss(data?: T): QuipResponse;
javascript(data?: T): QuipResponse;
json(data?: T): QuipResponse;
mime(type: ContentType, data?: T): QuipResponse;
jsonp(callback: string, data?: T): QuipResponse;
send(data?: T): QuipResponse;
}

type QuipResponseFunction = (data?: T) => QuipResponse;

export type QuipResponse = ServerResponse &
QuipExtensions & { body?: T };

interface Quip {
(req: IncomingMessage, res: ServerResponse, next: Function): void;
}

const quip: Quip;

export default quip;
}
```