update the filecache by setting mtimes to 0 when the mount configuration has changed instead of clearing the cache

mt_rand() is not secure from a cryptographic point of view, let's use openssl_random_pseudo_bytes() here

This token is completly useless since an attacker can easily extract it
from the page.

mt_rand() is not secure from a security point of view and predictable. Let's use openssl_random_pseudo_bytes() instead.

Before: 26 bits entropy
After: 72 bits entropy

Fix to preserve backward compatibility for apps creating static links containing the request token (currently the contacts app and maybe some 3rd party implementations)

etag has to be removed after version rollback to enable the sync client to detect the changes (bug #1829)

The mtime in the file cache has to be updated after version rollback (copy from outside of the regular files root) (fixes bug #1720)

Depreciated const can be removed after sync client update and release

- change update routine to add the namesapce to all stored properties

Include shared files in result

Thanks to mETz