Use hash part of URL for IE8 in files app

Before this fix, the URL wasn't updated in IE8 when navigating into
folders.

This fix makes use of the hash part of URLs to make this work in IE8,
since IE8 doesn't support the history API nor changing the URL without
redirecting.

From now, both the regular query URL "?dir=somedir" and "#?dir=somedir"
will work in both IE8 and non-IE8 browsers.

In IE8, query based URLs are automatically converted to hash URLs upon
page load. The conversion is done on the server side by redirecting the
user to the updated URL.

When loading a page directly using a hash URL in the form
"#?dir=somedir" in IE8, the server doesn't get the hash, so it will not
return any results in that case and rely on ajax to load the first page.