Create README.md

Some refactorization

adding migrations, a little cleanup

restricting related fields on API forms

missing filter

display edited invitations data

new viewset class for no creation/deletion, duplicating event data on invitation

show properly invitation events

let's not forget about the current day to be timezone aware...

Show per selected timezones.

store time in UTC, respecting timezones

weekly view, with raw data and no fancy formatting

adding functional tests

sample unit tests

Basic models, serializers and views for Invitations.