Load hipchat into riemann namespace

When trying to use hipchat with basic config:

```clj
(let [host "127.0.0.1"]
  (tcp-server :host host)
  (udp-server :host host)
  (ws-server  :host host))

(def hc (hipchat {:token "..."
                   :room "12345"
                   :from "Alert Robot"
                   :notify 1}))
(periodically-expire 5)
(let [index (default :ttl 300 (update-index (index)))]
  (streams
    (match :host "test01"
           hc)))
``` 

I got an error:

``` 
INFO [2013-12-10 17:36:26,647] main - riemann.bin - PID 81295

ERROR [2013-12-10 17:36:26,674] main - riemann.bin - Couldn't start java.lang.RuntimeException: Unable to resolve symbol: hipchat in this context, compiling:(etc/riemann.config:6:9)
``` 

Loading hipchat into the namespace fixes it.