dnsmasq should be disabled for minikube-net network with kvm/kvm2 driver

[viteksafronov]

Is this a BUG REPORT or FEATURE REQUEST? (choose one):
BUG REPORT

Please provide the following details:

Environment:

Minikube version: 0.25.2

• OS: Linux
• VM Driver: kvm2

What happened:
minikube uses by default two networks — default and minikube-net. First one has <forward mode = 'nat'/> and is not isolated. The second one is used for privates purposes and is isolated.
libvirt enables dnsmasq for both these networks by default, and so minikube (and kube-dns too) has two NS resolvers in its /etc/resolv.conf (192.168.39.1 and 192.168.122.1 for me). dnsmasq running on minikube-net has option no-resolv (which is set for isolated networks), so it always returns REFUSED for external lookups and the clients are getting errors from time to time.

What you expected to happen:

minikube should use only those NS which will resolve names.