Improves file not found exception in ir-archive
Improves file not found exception in ir-archive

An OSError exception has raised when file that should be archived wasn't found.
Replaced it with IRFileNotFoundException with a proper message.

Change-Id: Ib9c4164a2b2b036199bbbea8b8dae24e7ac77a75

okolisny/InfraRed,redhat-openstack/infrared,okolisny/InfraRed,redhat-openstack/infrared,redhat-openstack/infrared,okolisny/InfraRed