The AdaptError is only for internal use and should never be sent back to any public APIs such as the retrier. Previously, the AdaptError was being incorrectly sent to the retrier instead of the underlying error. This commit fixes the issue and also adds tests to ensure this is working properly.

Fixes issue where request property would always return `nil` if the url request was not used to create a URLSessionTask. This can commonly happen when an Error is thrown in an adapter.

It appears that in iOS 10 and macOS 10.12 that the root certificate is no longer included as part of the server trust object. The root certificate is still included in tvOS 10.0.

Nested Terminal commands and a blockquote under their respective instructions.

By adding the retryCount to the Request, the RequestRetrier protocol can use the retryCount to determine whether to continue to retry the Request.