Use django.utils.timezone.now() when determining if the due date of a component has passed to avoid tz-aware/naive datetime comparison bug

PHX-207 Accessibility Improvements

Toggle aria-hidden attribute on modal window open/close; Set title attribute on iframe to display name of component; Remove aria-labelledby attribute from modal body; Make modal overlay id attribute unique'

Do not pin dependency versions

Sprint Solutions:Zug PHX-200 PHX-201 XBlock LTI Consumer