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)
Should be
`(?m)^nameserver\s+127.*\n*`

But this still leaves an empty line.
<nameserver 10.16.60.14
nameserver 10.16.60.21
nameserver 127.0.0.1>
becomes
<nameserver 10.16.60.14
nameserver 10.16.60.21
>
Which makes it hard to test against.  With the check for the end \n, I get a clean test.