Add Control Sites

[guyellis]

Allow a config item on each site entry in the input that is called 'control' or something similar. Defaults to false if missing. This tells the script that we expect this site to be always available and use it to test our internet connection. e.g. google.com, yahoo.com, microsoft.com should always return 200 or 301. If they timeout then there's something wrong with our connectivity and we shouldn't assume a problem with the other sites. Run the control sites at the beginning and at the end.