Stores privileges information associated to a role. A role can have
privileges at three levels:
General level permissions.
Project level permissions.
Job level permissions.
Permissions must be checked from the top level to the lowest. It is, if a
role has a READ permissions at top level, an user with that role will be
allowed to read/execute any jobs in any project.
A role can have an ADMIN permission at two levels:
General level permissions: users with this role may perform any operation
(create/read/delete jobs, datasources and filter sequences).
Project level permissions: users with this role may perform any of the
previous operations restricted to the project level scope.