Adding pingdom functionality

Thought itd be nice to have alerts directly to IRC along with sms, calls, emails and everything else :+1: 
anton's interface really needs improving, but currently it does not allow the specification of a HTTP response code. Instead you should raise an exception which will be translated into a 500 in [anton.http#67](https://github.com/laterpay/anton/blob/ff2e0f5de51e3ff5423de5a662039c5e4e963630/anton/http.py#L67).