Correct typo kuberentes->kubernetes (#58)

This seems to be a common typo, possibly exacerbated by copy-paste
of comment strings. I spotted it in the README.md at first, so I fixed
that and then checked the rest of the code and fixed a few more. They
are all in comments or documentation, so there's no code issue.

FYI, there's still some in the vendor directory, but I haven't fixed
those as they'd get replaced by any new `go get` I think:

$ ack uberentes
vendor/k8s.io/apimachinery/hack/godep-deps.sh
20:# 2. godep restore based on k8s.io/kuberentes provided manifest

vendor/k8s.io/client-go/CHANGELOG.md
120:* Included bug fixes in k8s.io/kuberentes release-1.5 branch, up to

vendor/k8s.io/client-go/kubernetes/fake/register.go
64://     clientsetscheme "k8s.io/client-go/kuberentes/scheme"

vendor/k8s.io/client-go/kubernetes/scheme/register.go
64://     clientsetscheme "k8s.io/client-go/kuberentes/scheme"

Sorry, this isn't the most exciting commit in the world :-(

README.md

@@ -81,7 +81,7 @@ Available Commands:
 Flags:
   -h, --help                     help for virtual-kubelet
       --kubeconfig string        config file (default is $HOME/.kube/config)
-      --namespace string         kuberentes namespace (default is 'all')
+      --namespace string         kubernetes namespace (default is 'all')
       --nodename string          kubernetes node name (default "virtual-kubelet")
       --os string                Operating System (Linux/Windows) (default "Linux")
       --provider string          cloud provider
@@ -184,7 +184,7 @@ type Provider interface {
 	Capacity() v1.ResourceList
 
 	// NodeConditions returns a list of conditions (Ready, OutOfDisk, etc), which is polled periodically to update the node status
-	// within Kuberentes.
+	// within Kubernetes.
 	NodeConditions() []v1.NodeCondition
 
 	// OperatingSystem returns the operating system the provider is for.