update roles - for release v1.5.4
update roles - for release v1.5.4

 - arc-frontend: fix gocdb ldap endpoint mismatch
 - collectd and travis: minor testing updates
 - dhcp_server: start the service
 - dnsmasq: better defaults
 - fgci-install: ansible-pull script updates
 - pxe_bootstrap / pxe_config: speed and simplifications
 - slurm: slurm_jobcomp logrotate, reinstall improvements

mantti/fgci-tut,CSC-IT-Center-for-Science/fgci-ansible,mantti/fgci-tut,mantti/fgci-tut