Adding form

This PR aims to add:

- a controller
- a form to submit data (generate the forms `app/console doctrine:generate:form InnovareMainBundle:Servizi`)

Issues:
- Many To One Mapping Issue — Symfony — Doctrine
  `A "__toString()" method was not found on the objects of type "Innovare\MainBundle\Entity\Strumenti" passed to the choice field. To read a custom getter instead, set the option "property" to the desired property path.`
I fixed by adding:

```
    public function __toString()
    {
        return $this->modello;
    }
```