node.js crypto: Changed HMAC and Hash params to `any`

1. `createHmac` also accepts Buffers as the `key` param, not only strings
2. `Hmac.digest` and `Hash.digest` both return a Buffer object, if no encoding is specified, so also not just strings.

Docs:
http://nodejs.org/api/crypto.html

please use overload.

```
export function createHmac(algorithm: string, key: string): Hmac;
export function createHmac(algorithm: string, key: Buffer): Hmac;
```

https://github.com/joyent/node/blob/5344d0c1034b28f9e6de914430d8c8436ad85105/lib/crypto.js#L135