Remove linux driver warning if it is installed already
Remove linux driver warning if it is installed already

Case 1: the driver is installed

```
KVM driver is already available on your PATH at /usr/local/bin/docker-machine-driver-kvm
minikube is already available on your PATH at /home/j/.fabric8/bin/minikube
kubectl is already available on your PATH at /home/j/.fabric8/bin/kubectl
```

Otherwise

```
fabric8 recommends linux users use the docker-machine-driver-kvm driver
See https://docs.openshift.org/latest/minishift/getting-started/setting-up-driver-plugin.html#kvm-driver-install for setup instructions
Unable to download driver docker-machine-driver-kvm
minikube is already available on your PATH at /home/j/.fabric8/bin/minikube
kubectl is already available on your PATH at /home/j/.fabric8/bin/kubectl
```

fabric8io/gofabric8,fabric8io/gofabric8