Attest IE support or drop it

There are some conditional comments and shivs to support IE<9, but I'm unsure the entire website is working properly. For instance, trying a search with IE9 rendered the search text in the field of search results unreadable.

We got an OS account from browserstack.com and it should be used. If IE < 8 are unusable, those conditional comments should be removed accordingly. IE9 may work with some small fixes, though.

Also, an alert of "outdated browser" should be included.