[TASK] Use additional secret for apache delivery token

The access token is generated as a HMAC from the user
ids. As this would be valid for future requests
an additional token is introduced that will be cached
in configuration if the page is cached or
generated again on every rendering when the page is
not cached.

This can generate many files and folders and requires
the garbage collect feature to be implemented to
mitigate that.
[TASK] Reduce path parts for apache delivery publishing

The hash generated as part of the publishing path
was previously splitted in groups of four chars.

It has been agreed upon that it is enough to
have only one path part for that.

This change removes the splitting again
and adds the path part '0' for public files.