C++ backend, web frontend.

1. Yubikey OTP support
2. Web configuration UI
3. PAM module

1. Python used only to trigger the build, and it only calls CMake)
2. CMake
3. Yubiko libraries
4. Boost
5. WT++ C++ Web toolkit, used for the web GUI

0. Check all ranges when creating a key.
1. Add PIN as a second factor.
2. Configure user ID.
3. Implement PAM module.