Helppage

Closes #4

See merge request !40

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