Make ajax file list URL work in IE8

For browsers that don't support the history API,
the URL query will be stored in a hash
Automatically convert files URL to hash URLs for IE8 and less

Since IE8 and less don't support the history API, we need to use
hashchange as a workaround. To make this seamless the server will
initially convert the URL to a hash URL in such cases.
File list is now always ajax loaded

The file list is not returned any more by index.php in the "files" and
"files_trashbin" apps. The list will be empty and loaded initially
by the client using an ajax call.