Adds initial volumes package; Supports host-dirs

Adds the framework for external volume mounts.

Currently supports bare host directory mounts.

Modifies the API to support host directory mounts from Volumes
instead of VolumeMounts.
Adds EmptyDirectory volume struct

Adds EmptyDirectory to volumes. This represents a directory
on the host, given to a pod that should not persist beyond.

The current draft does not cleanup after itself.
API modified to use source; now supports EmptyDirectory

API is now modified to use a Source struct to handle multiple volumes.

Two volume types are supported now, HostDirectory and EmptyDirectory.
Add some more logging to service updates.
Operation server was not returning in error cases
Merge pull request #516 from smarterclayton/operation_server_not_returning

Operation server was not returning in error cases
kubelet: cleanup
Merge pull request #515 from brendandburns/fix

Add some more logging to service updates.
Merge pull request #517 from brendandburns/sanity

Turn off error checking prior to sanity checking.
Merge pull request #509 from xiangli-cmu/kubelet

kubelet: cleanup
Make build-release.sh not directory dependant.
Merge pull request #518 from MSOpenTech/shell-scripts

Make build-release.sh not directory dependant.
Merge pull request #452 from Sarsate/extvol-hostdir

Initial framework for external volumes.
Add a sleep to work around apparent races with salt.