Remove nameserver 127.0.0.1 line rather then dumping resolv.conf

We have a bug report complaining about docker dumping the contents of the
hosts resolv.conf if it container 127.0.0.1.  They asked that instead
of dropping the file altogether, that we just remove the line.

This patch removes the 127.0.0.1 lines, if they exist and then
checks if any nameserver lines exist.

Docker-DCO-1.1-Signed-off-by: Dan Walsh <dwalsh@redhat.com> (github: rhatdan)
Replace utils.CheckLocalDns with bytes.Contains line

Since RemoveLocalDns patch will  remove all localhost entries
from resolv.conf we no longer need anything more then
!bytes.Contains(resolvConf, []byte("nameserver")

To check for no nameserver entry in dns config.

Docker-DCO-1.1-Signed-off-by: Dan Walsh <dwalsh@redhat.com> (github: rhatdan)