Improve vagrant hostname support across cluster

This PR makes the following changes:

1. minion identifiers are now of the form "kubernetes-minion-1", "kubernetes-minion-2"
2. fixes host ip not being returned properly in the kubecfg list pods operation
3. vagrant etcd storage paths no longer need to use hostname_override
4. ability to ping by host name each node in cluster from every other node
It looks like the vsphere cluster configurations set this grain also.  If you change this you'll most likely break them.