Openx: adjustment for wheezy

```
$ apachectl configtest
apache2: Syntax error on line 171 of /etc/apache2/apache2.conf: Could not open configuration file /etc/apache2/httpd.conf: No such file or directory
```

`apache2` package doesn't create `/etc/apache2/httpd.conf` on `debian/wheezy`
`apache2` package creates empty `/etc/apache2/httpd.conf` on `debian/squeeze`