add(net-misc/ntp): Import current ntp ebuild.
fix(net-misc/ntp): don't install extra scripts and docs by default
fix(net-misc/ntp): Remove files from /etc and cleanup

Remove everything for openrc and do not install systemd drop-in configs
into /etc either. This simplifies things quite a bit.
fix(net-misc/ntp): update ntpd configuration

- Simplify ntp.conf, use generic pool instead of gentoo.
- Set drift file in unit so it doesn't need to be in ntp.conf.
- Run as ntp user if caps are enabled. This was previously done in the
  openrc service but not the systemd service.
- Add tmpfiles config to create /var/lib/ntp and /etc/ntp.conf
fix(net-misc/ntp): enable ntpd by default
feat(coreos-base/coreos): replace tlsdate with ntpd
Merge pull request #631 from marineam/ntp

Add ntpd, remove tlsdate