fix(dm): correct error in status code check
fix(dm): correct error in status code check

Also made an HTTPError error type to make it easier to type
switch on errors.

sparkprime/helm,sushilkm/helm,eicnix/helm,helm/helm,sushilkm/helm,jascott1/helm,helm/helm,qwangrepos/helm,yan234280533/helm,thomastaylor312/helm,iamzhout/helm,sparkprime/helm,sparkprime/helm,kdada/helm,sparkprime/helm,FengyunPan/helm,michelleN/deployment-manager,FengyunPan/helm,adamreese/helm,fibonacci1729/helm,adamreese/helm,jascott1/helm,technosophos/deployment-manager,jackgr/helm,jackgr/helm,kdada/helm,appscode/helm,rbwsam/helm,adamreese/deployment-manager,technosophos/deployment-manager,iamzhout/helm,adamreese/deployment-manager,bacongobbler/helm,sparkprime/helm,bacongobbler/helm,flynnduism/helm,fibonacci1729/helm,migmartri/helm,SlickNik/helm,appscode/helm,bradj/helm,flynnduism/helm,qwangrepos/helm,michelleN/deployment-manager,michelleN/deployment-manager,technosophos/k8s-helm,SlickNik/helm,bradj/helm,jackgr/helm,migmartri/helm,technosophos/deployment-manager,jackgr/helm,vaikas-google/deployment-manager,thomastaylor312/helm,technosophos/deployment-manager,yan234280533/helm,rbwsam/helm,vaikas-google/deployment-manager,adamreese/deployment-manager,jackgr/helm,adamreese/deployment-manager,eicnix/helm,technosophos/k8s-helm,technosophos/deployment-manager,michelleN/deployment-manager,adamreese/deployment-manager