Small fixes to update regex and add some exception management.

Added a really nice feature from PR vitorfs#220 fixing vitorfs#214 an…

…d done by @Vamoss

Expands documentation, adds a couples of fixes.

Fix vitorfs#197

Fix vitorfs#204

Updating most recent version of Django 3.0.3 to a less recent one bec…

…ause is unavailable for CI.

Quick fix on Django version for Travis tests.

Small updates and little bug fixes to the base code.

Fix vitorfs#183 from PR vitorfs#194 and vitorfs#195 from @bobrik-matej

Fixing minor bugs and pending issues.