Remove Managees field from User model
Remove Managees field from User model

The `Managees` field was implemented to track which users line-manager
other TimeOff users.

Remove it because:

a) it was premature; we don't yet have any features that use this

b) employees often need to have their leave approved by more than one
person and may need to share their leave calendar with other colleagues
without requiring their approval, so the 'manager-managee' model feels
to rigid; instead, we might have a list of users that are able to view a
user's leave calendar and another list of users that are required to
approve a user's leave requests - thanks to @rboulton for this
suggestion

mattbostock/leavediary