Add support for custom Mantid facilities files

Add an option to the config file to specify a replacement for Mantid's
default facilities XML file.  Also, add some code to verify that Mantid
recognizes the instrument specified in the config file.

Also changed packaging script to no longer put anything in /etc or
/etc/init.d.  (The main config and init.d files will almost certainly
have to be modified slightly by the sys-admins.  Since the distutils
package doesn't support the %config(noreplace) option in RPM's, if the
RPM installed the files directly into /etc and /etc/init.d, the
customized files would get overwritten during every yum update.)