Update salt config for apiserver to support Azure.
Add gce grain to salt config, change apiserver salt config.
Merge pull request #552 from MSOpenTech/azure-scripts

Update salt config for apiserver to support Azure.
Adds a flag to specify root working directory.

--root_dir specifies the directory kubelet will use for it's
procedures. Currently used for volume mounts.
Merge pull request #527 from Sarsate/rootdir-flag

Adds a flag to specify root working directory.