Allow expert_disk to be parameterized

Pass expert_disk to coi::profiles::cobbler_server as a parameter

Closes-Bug: #1325080
Merge remote-tracking branch 'origin/icehouse' into fix/1325080

Conflicts:
	manifests/profiles/cobbler_server.pp
Merge pull request #62 from CiscoSystems/fix/1325080

Allow expert_disk to be parameterized