Handle HTTP Redirects

[ghost]

Attempt to handle HTTP redirects nicely rather than immediately failing with a NetworkError.failedRequest(status:).

Reference: https://developer.github.com/v3/#http-redirects

[ghost]

We can get notified via a delegate to respond to redirects. Looks like the bulk of the work of constructing the new request is done for you. However, it does not appear to include the Authorization header.

References:

• https://developer.apple.com/reference/foundation/urlsessiontaskdelegate
• https://github.com/Alamofire/Alamofire/blob/b03b43cc381ec02eb9855085427186ef89055eef/Tests/SessionDelegateTests.swift#L427-L429