When performing a request via curl on Windows using schannel, ssl
certificate revocation checks does not handle verification failures
gracefully when an error is encountered that is unrelated to the actual
revocation of a certificate.
A new option is available to perform best effort revocation checks on
curl, so this is enabled by default on the Windows platform. A new
config option (`box_download_disable_ssl_revoke_best_effort`) has also
been added which can be optionally enabled to restore previous behavior
which results in a hard error if any error is encountered.
