RegressionwithDatePickerandcheckboxesonstockpage(catalogue>stock)

| Questions | Answers
| ------------- | -------------------------------------------------------
| Branch? | 1.7.4.x
| Description? | DatePicker field not working due to wrong css selector. Wrong usage of v-model in PsCheckbox.vue (https://fr.vuejs.org/v2/guide/forms.html#Checkbox)
| Type? | bug fix
| Category? | BO
| BC breaks? | no
| Deprecations? | no
| Fixed ticket? | Partial http://forge.prestashop.com/browse/BOOM-5620
| How to test? | Try to click on datepicker field, for example in product page, Available quantity field.

This change is