IMGAPI-52: imgapi: get error message from response body for 'getImageFile' endpoint
IMGAPI-52: imgapi: get error message from response body for 'getImageFile' endpoint

joyent/node-sdc-clients,joyent/node-sdc-clients,misterdjules/node-sdc-clients,arekinath/node-sdc-clients,arekinath/node-sdc-clients,misterdjules/node-sdc-clients