Add new parameter 'newsid' for run_instances

The 'newsid' only makes sense for Windows instance. If it's specified
as "True", the Windows instance will have new SID instead of the fixed
one from the image.

Signed-off-by: Osier Yang <osier@yunify.com>
Support generating new SID for Windows instances

New parameter "need_newsid" is added to "run_instances" and
"reset_instances". To keep back-compat, both APIs don't
generate new SID by default, ones who want to generate new
SID should explicitly specify "need_newsid" as True.

Signed-off-by: Osier Yang <osier@yunify.com>