Add the option to confirm the logout action

[visto9259]

The logout action in the User Controller will log out the user without allowing the user to confirm the logout.

Add the option to confirm the logout action:

• add an option to Module Options (lmcuser key) to enable/disable confirmation. The default should be 'disabled'.
• Create logout form. Add service to instantiate the form.
• Check the confirm option in the logout action, if disabled, perform the logout
• Check the confirm option in the logout action, if enabled, return a view with a simple form to confirm logout action. If confirmed, send a POST to the logout action
• In the logout action, if the request is a POST with a confirmation, perform the logout action