Rework error handling for swagger-client 3
Rework error handling for swagger-client 3

swagger-client 3 operations now reject with Error for response codes
>=400.  Replace response code checking with an error handler which
builds Error objects compatible with the existing API for this package.

Signed-off-by: Kevin Locke <ffb4761cba839470133bee36aeb139f58d7dbaa9@kevinlocke.name>

kevinoid/appveyor-status,kevinoid/appveyor-status,kevinoid/appveyor-status