Description:

Installs the basic framework for Acl9. Creates the necessary migration for
your new roles table and the join table for associating roles with users.

The optional arguments are as follows:

    subject:  if you want something other than 'User'
    role:     if you want something other than 'Role'
    objects:  space separated list of class names of objects that you can
              attach roles to (see the docs)

Examples:

`rails g acl9:setup`

    This will create:
        Migration:      db/migrate/XXX_create_role_tables.rb
        Role Model:     app/models/role.rb
        Config:         config/initializers/acl9.rb

    And it will update (or create a skeleton):
        Subject Model:  app/models/user.rb

`rails g acl9:setup account permission school classroom department`

    This will create:
        Migration:      db/migrate/XXX_create_permission_tables.rb
        Role Model:     app/models/permission.rb
        Config:         config/initializers/acl9.rb

    And it will update (or create a skeleton):
        Subject Model:  app/models/account.rb
        Object Models:  app/models/school.rb
                        app/models/classroom.rb
                        app/models/department.rb