Bug 2426: Remove deprecated management permission

Bug 2426: Remove deprecated management permission

After review of the code it turns out that the management permission
that has been marked as deprecated a long time ago, does not have
any function.

The patch removes all remaining code related to it.

To test:
- Make sure you have a patron with the management permission
- Apply patch
- Run database update
- Check everything still works as expected

Bonus:
borrowers.flags is recalculated for patrons with management
permission.

To check:
- Create some 'permission twins' with and without management
  permission
- Note the value in borrowers.flags
- Apply patch, don't run database update
- Save permissions from GUI for one of the twins
- Note the newly calculated value
- Run database update
- Now both twins should have the same borrowers.flags value

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>