Automatic merge from submit-queue

Fixes and improvements to Photon Controller backend for kube-up

- Improve reliability of network address detection by using MAC
  address. VMware has a MAC OUI that reliably distinguishes the VM's
  NICs from the other NICs (like the CBR). This doesn't rely on the
  unreliable reporting of the portgroup.
- Persist route changes. We configure routes on the master and nodes,
  but previously we didn't persist them so they didn't last across
  reboots. This persists them in /etc/network/interfaces
- Fix regression that didn't configure auth for kube-apiserver with
  Photon Controller.
- Reliably run apt-get update: Not doing this can cause apt to fail.
- Remove unused nginx config in salt