example.iana.org is down causing test failures

[daniel-dressler]

http://www.downforeveryoneorjustme.com/http://example.iana.org/

In relation to https://github.com/mozilla-servo/rust-http-client/pull/18/files I can only assume example.com was down once in the past prompting a transition to example.iana.org

Since we are not using the test's url in documentation perhaps google.com would be more reliable? The poor iana must have a hard time with example.com and if any website can provide an uptime guarantee that would be google.com

Any objections or can I make a pull request?

[daniel-dressler]

Looks like I pull requested too soon. Google tries to redirect thus the test fails.