Added further comments to the code surrounding the m_driveReadyDelayInSeconds attribute of CleanerSession

Disable server-side compilation on non x86_64 architectures. CASTOR server side needs Ceph, which is only available on x86_64.

Amended the fix to take into account clients that set an empty
protocol (yes, stager_put does that...), that was accepted so far.

Fixed tapeserverd changing its status to UP (instead of RUNNING) in the VDQM when "tpconfig up" is called while the session is running.

to work, the xroot-python-0.3 package is needed.