Add 'import-export' ressources for some apps

**Is your feature request related to a problem? Please describe.**

django-import-export is available in Bireli v0.5.0 however there is currently no apps which implement any resources so there is no "import/export" feature in any app.

**Describe the solution you'd like**

We should provide useful resources for some apps:

- Taggit ?
- Lotus but in fact it should be in its package;
- Request form.
