Add validation proccess for forms

[neeftarah]

Add a validation process (optional) to forms before creating tickets or sending to other destinations.

Form configuration:

- Add a field "The form need to be validated (Yes/No)"
- If the previous field is set to "Yes": Add 2 multiselect fields with validators (users with ticket validation abilities) to set witch users can be chosen by end-user to be the validator. (All validators by default).

Form entry (if the form need to be validated)

- Automatically add a field at the end of the form: "Choose a validator". A select field with allowed validator.
- The form is saved into database with a state "waiting for validation"
- A notification e-mail must be send to the chosen validator
- The validator can accept or refuse the form. If refused, a refused comment is required.
    - If accepted: The form is processed like now (ticket(s) creation)
    - If refused: the form get a status of "refused by validator" and can be edited by requester and resubmitted. A notification is sent to the requester when refused.

List of seized forms

- 2 blocs should be added to the form list:
    - "My forms (requester)" => (last 10 forms user submitted. status refused and waiting in priority)
    - "My forms (validator)" => (last 10 forms waiting for validation and with user as validator)
- A list page (with search engine) with:
    - all forms if user is validator or administrator
    - all forms submitted by user otherwise
    - A link button near "search" and "config" buttons in toolbar

[neeftarah]

Done