This fixes an "OSError: [Errno 2] No such file or directory" on Fedora 23. Note that openssl-devel was not sufficient to install the openssl commandline tool.
The current manual-testing build of le-auto now crashes with #1548, but that should have been resolved when we upgraded the cryptography lib and so should go away when we build a new version.
Originally, I had it in mind to move letsencrypt-auto inside this dir. However, now we'd like to copy it or link it to the root level, where people are used to finding it (at least for awhile). Since it would be confusing to have a letsencrypt-auto and a letsencrypt_auto right next to each other, we rename this folder.
