Allow running hack/verify-spelling.sh from any directory
Allow running hack/verify-spelling.sh from any directory

Previously if script was not run from root repository directory it
was failing with following error:

```
can't load package: package k8s.io/github.com/client9/misspell/cmd/misspell: cannot find package "k8s.io/github.com/client9/misspell/cmd/misspell" in any of:
  ...GPATH ENTRIES...
```

mmerrill3/autoscaler,kubernetes/autoscaler,bskiba/autoscaler,kubernetes/autoscaler,mmerrill3/autoscaler,bskiba/autoscaler,bskiba/autoscaler,kubernetes/autoscaler,kubernetes/autoscaler,mmerrill3/autoscaler,mmerrill3/autoscaler