* Migrate to Python 3
* Update token generator mechanism
* Switch to Bootstrap 4
* Switch from Iconmonstr to Font Awesome icons
* Rename default CA common name to "Certidude at ca.example.lan"
* Add self-enroll for the TLS server certificates
* TLS client auth for lease updating
* Compile assets from npm packages to /var/lib/certidude/ca.example.lan/assets
* Save token secret to config
* OpenVPN profile fixes for Ubuntu 16.04
* Raise correct exceptions for invalid tokens
* Display token expiration time in local time