To check descriptor format sense data handling we need a source.
Clean up some other problems and improve support for st.

Changes:
   - add 'dsense' option to generate descriptor sense data
     format (default still fixed format)
   - correct unit attention generation (only INQUIRY, REQUEST_SENSE
     and REPORT_LUNS ignore it)
   - better information sent to log in "noisy" mode (i.e. opts=1)
   - correct and expand standard INQUIRY response, include version
     descriptors
   - filter MODE_SENSE command so that subpage!=0 generates error
   - add REWIND (SSC) command support (NOP)
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>