PostgreSQL causing slow shutdowns with OS X Server in Mavericks
The com.apple.DeviceManagement.postgres line makes me think that this could be related to Profile Manager services. Does it show Profile Manager running in Server.app? If you're not utilizing this service, disabling it may help to stop the shutdown delays.

Alternately, if you need to keep these services running, it may be worth looking at some log files somewhere (/var/log/system.log or /var/log/devicemgr/*?) to see if the profile manager service (or any others) are complaining.