Adding MetWit lookup

Includes

 - PHP `CAW\Curl` class. General purpose class for curl requests.
 - PHP `CAW\MetWit` class for interaction with metwit.com API
 - JS `metwit.js` for interaction with `CAW\MetWit.php`
 - Simple implementation in application

Let me hear your thoughts! 
I just invalidated this token. We should figure out a way to apply this in a safe manner.