Fixed exporter function in Users module in 1.4... like #1630 in 1.3

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | no
| License       | MIT
| Doc PR        | -

Some details:

- Detected Error is in module-Users, func-exporter when submit the form. The problem is in the template: it must post the *csrftoken*.
- #1630 PR try to arrange this issue on 1.3 branch
- This PR applies the same change (no tested) on 1.4 branch