bugfix: federation range #547

Example to test:

  <sib-form
    fields="users"
    range-users="https://api.test-paris.happy-dev.fr/sources/circles/"
  ></sib-form>

With this bugfix comes:

• update of the examples following the fix of !297 (merged)
• make the store.initGraph return the fetched resource to improve the syntax of the code