Proof of concept / testing only!

Usage:

``javascript
var signature = require("signatures");

var requestParams = {
hostname: host,
path: '/',
port: 8081,
method: "POST",
headers: {
'content-type': 'application/json',
'date': new Date().toUTCString(),
}
}

var sign = signature(
'my-key', // keyId
'6Jj3c7lQr6dhDf4oMsYnTfrjFnwezP4GzqHlqr2heyw=', // key
'hmac-sha256', // Hashing algorithm
['date', '(request-target)'] // Headers to sign
);

var signature = sign(requestParams);
requestParams.headers.authorization = signature;

var req = http.request(requestParams)
// ... etc
``