IE 9+ fixes

* Fix making PUT/DELETE requests by uppercasing the HTTP method name
* This also fixes PATCH for Chrome/Safari
* Fix requests with undefined body on IE
* IE 9 fix for connection error
* Fix CSS being applied to test suite

The only test that now fails is the FormData test on IE 9. Maybe we should skip that test if FormData is unavailable?
@dgraham Now rejecting everything that's not 100..599