Make sure action plugin copy cleans up tmp dir

The copy action plugin creates its own tmp dir for each file that it
copies to the target machine.  However, it does not clean up the
original tmp path it was given when run() is called.  This cleans up the
tmp path before it begins looping on source files.
Merge pull request #5384 from sfromm/cleantmpdir

Make sure action plugin copy cleans up tmp dir