Rely on container-selinux for centos/fedora25/rhel

RH now provides `container-selinux` which provides everything we need
for docker's selinux policy. Rely on `container-selinux` where
available, and `docker-engine-selinux` when not.

This still builds the `docker-engine-selinux` package and presumably
makes it available, but is no longer a requirement in the
`docker-engine` package preferring `container-selinux` instead.

`container-selinux` is available on fedora24, however the version that
is available does not set the correct types on the `dockerd` binary. We
can use `container-selinux` and just supplement that with some of our
own policy, but for now just keep using `docker-engine-selinux` as is.

Signed-off-by: Brian Goff <[email protected]>

Author: cpuguy83