Code review comment for lp://staging/~rackspace-titan/nova/osapi-servers-cleanup-p1

PEP8 fixes: 8-9, 39-40, 48-49

Explanation in exceptions: 21-22, 30-31, 56-57, 151,

Return-code fixes: 601-602, 605-606, 657-658, 661-662, these return codes didn't make sense in their current form. If you're missing 'flavorId' is a bad request, not an unprocessable entity.

I've also added "request.context" and "request.reservation_id" to the wsgi.Request object, which accounts for a good deal of this MP.

It's a pretty big prop, and I wanted to make it smaller, so let me know if you think I should remove some things or do it differently.