Based on my discussions with Pete Zaitcev <zaitcev@redhat.com>, I'm
convinced that globally re-writing the START_STOP command into a
TEST_UNIT_READY command is a good idea.  This is supported by the fact
that:

(1) Lots of devices don't support START_STOP
(2) Those that do support it often don't do a good job
(3) Win/Mac will never send these commands over a USB bus

So, here's a patch that re-writes them into Test Unit Ready commands.  It
seems to work on my system, but needs more testing.  There may be a problem
with this code still.... it seems that the SCSI layer can get convinced
that the unit is not ready permanently.  I'm honestly not certain what bit
of code is wrong where, so reports from others would be greatly
appreciated.