A SimpleAccountRealm that enables text-based configuration of the initial User, Role, and Permission objects created at startup. <p/> Each User account definition specifies the username, password, and roles for a user. Each Role definition specifies a name and an optional collection of assigned Permissions. Users can be assigned Roles, and Roles can be assigned Permissions. By transitive association, each User 'has' all of their Role's Permissions. <p/> User and user-to-role definitions are specified via the {@link #setUserDefinitions} method and Role-to-permission definitions are specified via the {@link #setRoleDefinitions} method.