IE 6 & 7 support ending

[pmeenan]

I will be taking down the IE 6 and IE 7 testers in Dulles in the next week or so. With the end of support for XP there is no good way to run the browsers on a public-facing service without expecting them to be hacked.

The code will still support testing IE 6 and IE 7 in private instances, just not from the public Dulles location (and potentially other locations as well).