Backport of #3951 to stable5

Squashed commit of the following:

commit 46c1280e4f2ac61f0b3c5fed9d2a516cb000c009
Author: Thomas Müller <thomas.mueller@tmit.eu>
Date:   Fri Jul 5 13:45:21 2013 +0200

    proper fix for getting the shared item if no user is logged in

commit 99e32baec4464444a1a46ae47321e0378e367c3e
Author: Thomas Müller <thomas.mueller@tmit.eu>
Date:   Fri Jul 5 13:22:38 2013 +0200

    php 5.3 compliant now

commit 227e5f10016e362ed1302acb4426de391d4d9b4b
Author: Thomas Müller <thomas.mueller@tmit.eu>
Date:   Fri Jul 5 12:15:47 2013 +0200

    get the real physical folder name for anonymous upload