6-12-09 - Rob Mosher
*Changed the action 'type' to 'system', adding functionality for 'user' hooks.
*No longer using insecure 'SELECT *' on 'role' database.
*Allows any role but anonymous user. Can now send e-mail to all authenticated users through a Trigger.
*Validates that at least one role is selected if 'selected node types' is selected.
*Allows %username substitution in e-mails.