fix calendar upcoming view: when event is all_day, and ended yesterday, it was considered as ending today because of UTC time
(cherry picked from commit d8860a62052feba81a7d3d711de3b6102c2137ab)
fix filter when value is zero which is different from null
(cherry picked from commit 6085f6418ca2bee8803852fda82e19a9d9761e25)
fix calendar view, when loading of calendars and view are parallel, we may see 2 times the same event
(cherry picked from commit 672f001cca464678bb75671dea1fc8e43b371c4f)
fix when remove can have implications from root model to sub models
(cherry picked from commit 07010ca74af5e6672fba63437c1fe09b9ab4da75)
make sure we won't remove files if the database is not working
(cherry picked from commit 5dde6b52353b0cec1a24999c64cda2039e19c34a)
fix google calendar attendees
fix picture from google
improve 'who' section in event screen
add creator for events
small improvement of event screen look
Merge branch 'master' of https://github.com/passerellesnumeriques/Students-Database into dev