Create include.js tests

[jaredhirsch]

BrowserSupport - use useragent npm package to generate a list of UA strings, verify that our sniffer does what it should.

Also mock out WinChan and test that the public and internal APIs behave properly. Just get some kind of protection in place :-)

[jaredhirsch]

We can also start to rethink whether we need/want to be sniffing user-agent strings, it's just so gross

[shane-tomlinson]

This was touched upon in #483 and #1199, I am very surprised there is not already an open issue about this.