mitchellh/vagrant — pull request #1754 by sthulbourn (2013-05-21 10:49:11+00:00)
Title: Client certiciate curl option

I had the issue with downloading boxes from servers protected with a client certificate.

I've added a way to pass client certs in with a `--cert file` param:
```sh
bundle exec bin/vagrant box add responsive https://boxes.dev.bbc.co.uk/news/responsive.box --cert $DEV_CERT_PATH
```

`vagrant box add -h` provides details