Introduce support for handling box architecture. Adds a new
`box_architecture` setting that defaults to `:auto` which will perform
automatic detection of the host system, but can be overridden with a
custom value. Can also be set to `nil` which will result in it fetching
the box flagged with the default architecture within the metadata.
Box collection has been modified to allow existing boxes already
downloaded and unpacked to still function as expected when architecture
information is not available.
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.
This makes sure that config.vm.box_download_checksum and
config.vm.box_download_checksum_type get passed to
Vagrant::Action.action_box_add with other options on
box download/import.
https://github.com/mitchellh/vagrant/pull/4282 introduced new setting to set alternate vagrant cloud server URLs, but it doesn't work actually.
This PR helps to process the value correctly.
