!!! [v6r9] Fix r mand storage 

This PR is necessary for being able to change the SAPath of an existing SE. In particular mandatory for being able to move CERN-USER from Castor to EOS. Also for (finally) get rid of /t0d1/ /t1d0/ at CNAF!
For v6r10, Chris is preparing an RFC and started to look at refactoring the code in order to make it cleaner