Fixed race condition when creating and dropping DB connections. This was exposed by stress tests and the culprit was that any client wanting to inspect this class by calling hasattr() would have called getattr(), which internally creates a connection

Conflicts:
	h/Ctape_constants.h
	tape/cvtden.c

Added the open and close time in the disk/non-disk time ratio calculation in disk tasks (close is the most important).

Updated the example castor.conf accordingly.
Removed reference to now gone repackd in castor.conf example.
Removed unused entried in rtcp_constants.h and replaced rtcpd_constants.h by constants in tapeserver/daemon/Constants.hpp.

Added better measurement of the disk performance to locate slow disk servers during tests in production.

Fixed creating the wrong type of DiskWriteFile when we have non-xroot mode and non-URL path.

This unfortunate move is necessary because the error/exception
handling of rmcd is done using the TCP/IP connection with the
client.