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.
PodInfo should indicate when a pod is not found

Client should react.  Also, dial down the chattiness of errors for
pods which do not exist and stop processing NotFound earlier in
the podinfo chain
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.
Merge pull request #512 from smarterclayton/communicate_missing_pod_info

PodInfo should indicate when a pod is not found
Refactor Kubelet config sources for clarity

Create a new "Pod" concept which can identify pods from
many config sources.
Switch the Kubelet to use kubelet/config

Also transfer the Kubelet from using ContainerManifest.ID to source specific
identifiers with namespacing.  Move goroutine behavior out of kubelet/ and
into integration.go and cmd/kubelet/kubelet.go for better isolation.