Fedora CoreOS support (#5657)

* fedora coreos support
- bootstrap and new fact for

* fedora coreos support
- fix bootstrap condition

* fedora coreos support
- allow customize packages for fedora coreos bootstrap

* fedora coreos support
- prevent install ptyhon3 and epel via dnf for fedora coreos

* fedora coreos support
- handle all ostree like os in same way

* fedora coreos support
- handle all ostree like os in same way for crio

* fedora coreos support
- add fcos documentations

README.md

@@ -83,6 +83,7 @@ vagrant up
 - [Network plugins](#network-plugins)
 - [Vagrant install](docs/vagrant.md)
 - [CoreOS bootstrap](docs/coreos.md)
+- [Fedora CoreOS bootstrap](docs/fcos.md)
 - [Debian Jessie setup](docs/debian.md)
 - [openSUSE setup](docs/opensuse.md)
 - [Downloaded artifacts](docs/downloads.md)
@@ -105,6 +106,7 @@ vagrant up
 - **CentOS/RHEL** 7
 - **Fedora** 28
 - **Fedora/CentOS** Atomic
+- **Fedora CoreOS** (experimental: see [fcos Note](docs/fcos.md)
 - **openSUSE** Leap 42.3/Tumbleweed
 - **Oracle Linux** 7