Enable use of eups environment in etc/init.d/mysql-proxy
Enable use of eups environment in etc/init.d/xrootd
Separate paths management for Qserv services

- init.d/path.cfg.sh loads paths in environment using eups or
  meta-config file,
- source_sysconfig() loads parameters for Qserv services
  from etc/sysconfig/service-name.
Enable use of eups environment in etc/init.d/mysqld
Enable use of eups environment in etc/init.d/zookeeper
Improve one configuration error message