move spray logic from ftslave

The current implementation of starting up an ftslave instance to perform a spray doesn't map very well to the cloud.  I can think of two possibilities:

• move the logic from ftslave to dafilesrv - since dafilesrv is likely to be running (replicated) in a cloud system to allow remote and external access to files.
• allow the copies to be done locally within dfuserver - still on separate threads if needed.

Eventually most of the common operations should be done by cloud api calls (if no translation).  Using dafilesrv may give better scaling - so the transfer will not be bound by the network bandwidth for a machine.  I'm not sure if dfuserver as it is currently implemented can be replicated.  The copying code should have no problems, but not sure about code that checks for file events.

I'm not sure which I prefer.  A "hacked" version running locally is probably easiest to implement.

jakesmith any thoughts?