Fix typo in comment message
Fix typo in comment message

an request => a request
rest => resp
exception_from_response() => exceptions.from_response() '.' operator means call
from_response() in exceptions module.

Change-Id: I5e780dd2882b39d1b39f7c64bf274e90934c09ec
Signed-off-by: Lin Yang <984c62e29c173058275d217ee55de7058aa509b9@intel.com>

scottdangelo/cinderclient-api-microversions,scottdangelo/cinderclient-api-microversions