Roles Interceptor
This interceptor ensures that the action will only be executed if the user has the correct role.
Parameters
- allowedRoles- a comma-separated list of roles to allow
- disallowedRoles- a comma-separated list of roles to disallow
When both allowedRoles and disallowedRoles are configured, then disallowedRoles takes precedence, applying 
the following logic:
  (if ((inRole(role1) || inRole(role2) || ... inRole(roleN)) &&
       !inRole(roleA) && !inRole(roleB) && ... !inRole(roleZ))
  { //permit ...
Examples
  <!-- only allows the admin and member roles -->
  <action name="someAction" class="com.examples.SomeAction">
      <interceptor-ref name="completeStack"/>
      <interceptor-ref name="roles">
        <param name="allowedRoles">admin,member</param>
      </interceptor-ref>
      <result name="success">good_result.ftl</result>
  </action>
