Specs for HTTP auth through bundle config.
Initial implementation.
Raise better exceptions if authentication fails.
Extract a variable for "exceptions to not retry."
Refactor auth retry into its own method.
Intercept 401s or 403s for other requests.

Everywhere CertificateError is handled separately, to be precise. Just in case
the API suddenly decides you need to be authenticated I guess.
Take :focused out of the specs.
Oops, left a debugging statement in.
Merge pull request #2825 from smashwilson/credentials

Private access credentials