habbix: cool main app with {hosts, apps, items, history} outputs.

`habbix help` for usage instructions:

   hosts            List all hosts and groups (except templates)
   apps <hostid>    List available "metric groups" for the host
   items <appid>    List available "metrics" in the metric group <appid>
   history <itemid> Print out <time>,<value> for the given metric <itemid> for usage instructions