Ability to add custom roles for managing access control in ACLs.
A similar effect can be achieved by using groups, but in some cases you may want users in groups, and the group to have a custom role, and this should be achievable without nesting groups which is not explicitly supported and could have other complications.
Implements a CustomRoleProvider with custom.properties setting:
etc/custom.properties, comma-separate list:
org.opencastproject.security.custom.roles=ROLE_ONE, ROLE_TWO, ROLE_THREE