[imp] IMP 6.2 & IE 11 & dynamnic mode - forever loading

[Rick Romero]

  Quoting Michael M Slusarz <slusarz at horde.org>:

> Quoting Rick Romero <rick at havokmon.com>:
>
>> I seem to have a problem with IMP 6.2 and IE 11 - when logging in with
>> dynamic Mode, the mailbox never loads.
>> ('Loading...' is always displayed.)
>
> Works fine for me.

Yeah I don't use IE (so no garbage) on Windows 7 Pro.  Other Windows
7/IE11 users complained after I updated to 6.2.0, which is why it came up.
I'm on Debian - so maybe there's a (IE11 only?) problem with the
non-official Debian packaging. \o/  But I only notify the list because
it's not just me, though it may just be my install.

This is 2nd time I've had to force IE10 compatibility, so I have no issue
just throwing the header code in PageOutput.php (I already modify
Mime/Headers.php on upgrades, so it's in my expected change list.)

Rick