Devices are being disabled due to licensing restrictions even if not all ports are being used

[rstanca]

Steps to reproduce, this is for a licence key that allows 4 devices:

OS: Ubuntu 16.04
Version: Bluecherry 2.8.2

1. add 4 devices
2. remove 2 devices
3. try to add another device again, it will be disabled

Restarting the bluecherry server will fix this.

Reference ticket: http://support.bluecherrydvr.com/helpdesk/tickets/1691