Cinder monkey patching review

Several cinder services do eventlet.monkey_patch() i.e. monkey patch everything that has an eventlet alternative. We should really consider a more conservative approach to doing this for the following reasons:

1. monkey patching everything increases the likelihood of unexpected results since you are using eventlet alternatives to modules which may not behave the same.
2. monkey patching everything is normally restricted to testing
3. other openstack services e.g. Glance use a whitelist approach so they know exactly what modules are being monkey patched thus making it easier to target tessts.
4. patching everyting makes it harder if you want to use a non-patched/original module