[WIP] Using nginx to port forward instead of iptables.

Fixes #537.
Missing a `:` here.

```
ashl6947@MMN1F3FD58 ~/writing/developer.rackspace.com (pr/538=) $ script/deploy -v --skip-tags monitoring
ERROR: Syntax Error while loading YAML script, /Users/ashl6947/writing/developer.rackspace.com/deploy/jenkins.yml
Note: The error may actually appear before this position: line 113, column 13

            proxy_set_header "Host $http_host"
            proxy_pass: http://127.0.0.1:8080
            ^
```