Adding/deleting enrollments in HBAC/Sudo Rules tabs fails. The facets for these associations need to be configured to call the right commands.

Steps to reproduce add problem:
1. Go to Identity -> Users.
2. Click one of the users and click HBAC/Sudo Rules tab.
3. Enroll the user into an existing HBAC/Sudo rules, an error will appear: unknown command u'user_add_member'.

Steps to reproduce delete problem:
1. Add a user into the Who category of an existing HBAC/Sudo rules.
2. Go to Identity -> Users.
3. Click the user used in step #1 and click HBAC/Sudo Rules tab.
4. Delete the HBAC/Sudo rule enrollment, an error will appear: unknown command u'user_remove_member'.

Similar problem happens with all entities that can be a member of HBAC/Sudo rule (i.e. groups, host, host group), sometimes without any error message.