Added IE 11 DNS error page

Addressed Issue #2 (partially)

IE 11 detection is a tad tricky (BrowserDetect incorrectly identifies it), but what I added should do. There is a diagnose button which calls `window.external.DiagnoseConnection()`. I'm not sure if this is callable from a non `res://ieframe.dll` page, but if it is this should work. If not, it will be similar to the issue with the more button in Chrome.