twisted的getPage已经不建议使用，新接口为twisted.web.client.Agent

Twisted-16.7.0 is coming soon, and it deprecates twisted.web.client.getPage (and client.HTTPClientFactory). We use these in some of the unit tests, to fetch one of the HTTP WAPI/WUI pages and make sure the contents look right.

We need to change these tests to use twisted.web.client.Agent instead, or a package named "treq", which is a Twisted flavor of the excellent (but blocking) requests library.