Make role::graphite work in Labs

* Add configuration to allow changing the apache auth system from ldap
  to file based auth.
* Allow changing hostname.
* Allow changing carbon storage directory
* Mount secondary disk at /srv for labs instances
* Move monitor_service for reqstats_5xx into production-only block
* Wait until filesystems are mounted and network interfaces are up
  before trying to start carbon upstart jobs

Change-Id: Ice77564fc9fee86bd761d293b286c291098b89b5