Add sleep times for events

[equetzal]

Sometimes when running large events, powering on and off the computers is a long task for the staff members. Adding a functionality for hibernate computers (like using rtcwake) during certain periods (eg. at night / not being used), can help to kind of 'shutdown' computers and save energy in the meanwhile. It's not possible to configure this to PowerOff + PowerOn because that is BIOS-dependent, so it might not work on all enviroments.