Wrong User Agent when selecting IE8

[pmeenan]

I'll check the Dulles agents to make sure they all have they latest updates (they should because they are set to auto update but some may have lagged).

I'll have to see if there is a way to disable compatibility mode on a per-test basis. If so then I can expose it as an option but the default will be to use the requested version of IE but to let it run as it would normally.