refs #8432 - change foreman.url to proxy.url, support sending to proxy

1) rename foreman.url to proxy.url
2) add a parameter ```proxy.type``` (which should be set to ```proxy``` for smart proxy)
3) if ```proxy.type == 'proxy'``` then alter the url to smart proxy url.
how about 
``` ruby
facts_path = (proxy_type == 'proxy') ? "#{uri.path}/discovery/create" : "#{uri.path}/api/v2/discovered_hosts/facts"
```
and using one line of `req=`?
I think it will be a little easier to read