Fix setting title
[mms] Allow any HordeCore AJAX response object to return JSON-HTML output, instead of pure JSON.
Force AJAX return to JSON-HTML when submitting via IFRAME

Otherwise, IE8 will display a popup download message instead of
redirecting to login page

Has the ancillary advantage that it will allow sessions to continue even
if MAX POST size is reached, since token/SID information is in URL and
won't be thrown out by PHP like it does with all POST variables.