Add mini calendar for each user
This will replace the current availability info that shows up in the users list.
The user's availabilities should show up as light grey. Shifts are dark grey.
The function of the mini calendar is to provide an at-a-glance overview of the user's current state for shifts and availabilities.
![image](data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw==)