Add post-giddyup webhooks

Each test result plus the related Giddy Up information is posted to each
webhook in the configuration. The first user is Bishop, so it can keep
track of tests as they happen and annoy the hell out of Engineering.
An example configuration:
```erlang
    ,{webhooks, [
                [{name, "Bishop"},
                 {url, "http://basho-engbot.herokuapp.com/"}]
                ]}
```