Update "_get_by_name_or_id" method so it's consistent with "_get_by_ref_or_id" and throws if a resource is not found.
Update "_get_by_name_or_id" method so it's consistent with "_get_by_ref_or_id"
and throws if a resource is not found.

This is important since without di RBAC and many other things don't work
correctly.

emedvedev/st2,punalpatel/st2,tonybaloney/st2,emedvedev/st2,pixelrebel/st2,Plexxi/st2,punalpatel/st2,peak6/st2,lakshmi-kannan/st2,tonybaloney/st2,StackStorm/st2,tonybaloney/st2,pixelrebel/st2,emedvedev/st2,StackStorm/st2,punalpatel/st2,lakshmi-kannan/st2,lakshmi-kannan/st2,StackStorm/st2,StackStorm/st2,Plexxi/st2,pixelrebel/st2,Plexxi/st2,Plexxi/st2,peak6/st2,peak6/st2,nzlosh/st2,nzlosh/st2,nzlosh/st2,nzlosh/st2