SSL configuration and authentication for the HTTP check

[rbague]

While implementing some HTTP status checks that we use in one of our applications, I noticed that the HTTP check skips SSL certificate validation in HTTPS requests, and that it does not use the authorization credentials if provided in the URI, which required us to monkey-patch it so we can use it.

This PR fixes both of those things.

• Verify the SSL certificate on HTTP requests
• Add basic authentication to the request, if it's present in the URI

Let me know if you need me to change anything in order to get it merged!