Remove create_from* functor jump table
Remove create_from* functor jump table

To make it easier to debug during runtime which method was
called remove the dictionary type -> functor mapping and
use a set of if statements instead. This makes it so that
if one of these methods fails we can gather more information
from the traceback than what was previously possible.

Change-Id: Iee2b0b90fe57734966d415c053bbc967335d5509

scality/cinder,openstack/cinder,tlakshman26/cinder-bug-fix-volume-conversion-full,CloudServer/cinder,alex8866/cinder,github-borat/cinder,sasukeh/cinder,tlakshman26/cinder-bug-fix-volume-conversion-full,Nexenta/cinder,scottdangelo/RemoveVolumeMangerLocks,rakeshmi/cinder,eharney/cinder,nikesh-mahalka/cinder,ge0rgi/cinder,abusse/cinder,JioCloud/cinder,phenoxim/cinder,rakeshmi/cinder,dims/cinder,blueboxgroup/cinder,bswartz/cinder,petrutlucian94/cinder,cloudbase/cinder,NetApp/cinder,potsmaster/cinder,leilihh/cinder,blueboxgroup/cinder,NetApp/cinder,Datera/cinder,Akrog/cinder,julianwang/cinder,j-griffith/cinder,Paul-Ezell/cinder-1,julianwang/cinder,hguemar/cinder,openstack/cinder,phenoxim/cinder,petrutlucian94/cinder,redhat-openstack/cinder,duhzecca/cinder,Nexenta/cinder,JioCloud/cinder,scottdangelo/RemoveVolumeMangerLocks,Akrog/cinder,scality/cinder,Datera/cinder,saeki-masaki/cinder,nexusriot/cinder,potsmaster/cinder,github-borat/cinder,nikesh-mahalka/cinder,takeshineshiro/cinder,Paul-Ezell/cinder-1,saeki-masaki/cinder,hguemar/cinder,bswartz/cinder,dims/cinder,cloudbase/cinder,mahak/cinder,apporc/cinder,eharney/cinder,CloudServer/cinder,tlakshman26/cinder-new-branch,Accelerite/cinder,winndows/cinder,tlakshman26/cinder-new-branch,sasukeh/cinder,abusse/cinder,apporc/cinder,Accelerite/cinder,j-griffith/cinder,Hybrid-Cloud/cinder,Hybrid-Cloud/cinder,alex8866/cinder,leilihh/cinder,takeshineshiro/cinder,manojhirway/ExistingImagesOnNFS,duhzecca/cinder,tlakshman26/cinder-https-changes,manojhirway/ExistingImagesOnNFS,mahak/cinder,nexusriot/cinder,redhat-openstack/cinder,winndows/cinder,tlakshman26/cinder-https-changes