I feel it'd be confusing to use kasmvnc group to provide access to the
TSL certificate. Groups like that control whether you can run software,
e.g. "docker" group. Using "-cert" clearly shows it's just for
certificate access. Not unlide ssl-cert group in Debian.
Even if I set rpm as conflicting with TigerVNC, update-alternatives
breaks in post-install. That is because files like /usr/bin/vncserver
are left from TigerVNC, when post-install runs.
So, I chose to use /usr/bin/vncserver without update-alternatives.
