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.
there is only one type of url we support, which is ```proxy.url``` this message will confuse users who send ```proxy.url=http://foreman proxy.type=foreman```

I'd like to normalize this - we'll have only **one** url type which is ```proxy.url``` and according to the ```proxy.type``` we will know if the ```proxy.url``` is foreman or smart-proxy.