add pip packaging process

See merge request !39

Updated deployment docu and asgi.py to use daphne as asgi server

See merge request !37

Issue #17: added threading for invitation emails and feedback for whether email sending failed

Closes #17

See merge request !36

channel redis is needed for redis backend deployment

* added threading for invitation emails to avoid wsgi timeouts for big elections
* added email success/failure feedback for the sending of invitations in the session's management. This is done asynchronous with django channels and modals and alerts that show the failed email addresses

Feature reload

Closes #15

See merge request !35

Sort election in a more advanced way

See merge request !34

* removed double shadow in the election view
* reduced default value for election to 5 min
* removed old todos