Deploy may fail due to dhcp options not existing, but image gets left in the cache

While doing some testing work, I discovered if you fail a deployment, for example by not having the ability to setup the DHCP options due to a VIF, the image which may have been previously downloaded by the image cache, may be orphaned until other wise cleaned up or replaced, which can be frustrating.

Ideally, upon such a failure and state transition, the conductor *might* want to delete the disk image from the cache on disk to minimize potential operator confusion.