Since systemd unit can override parameters using drop-in unit, we don't need
mustache template for them.
Also, drop --disttype option on install.sh since it does not required anymore,
introduce --sysconfdir instead for non-redhat distributions.
Move package build script from .rpm/.deb to single script, install.sh.
We need this to support nonroot mode, and also to keep package build script
consistent between .rpm/.deb.