scsi tgt

The following patchset adds the basic infrastructure to support target mode in userspace. There are sevreral todo's left. They mostly require changes around us like to the packet layer, request queue etc. For Jeff's suggestion we are working on the packet layer suggestion, but are also looking into relayfs as a possibility.

This is not ready for mainline. Maybe ready for James to manage it in a tree, but not ready for heavy use. With some outstanding patches Tomo can install SLES to a scsi tgt LU. But we still need to add a lot of functionality to userspace. We basically need to add the state model code we just ripped out of the kernel to userspace becuase the current code is geared tword working on trying to maintain performance with a kernel implementation not add features/requirements like task management functions, support for tape and cd, etc.