Portworx Volume Driver in Kubernetes

- Add a new type PortworxVolumeSource
- Implement the kubernetes volume plugin for Portworx Volumes under pkg/volume/portworx
- The Portworx Volume Driver uses the libopenstorage/openstorage specifications and apis for volume operations.

Changes for k8s configuration and examples for portworx volumes.

- Add PortworxVolume hooks in kubectl, kube-controller-manager and validation.
- Add a README for PortworxVolume usage as PVs, PVCs and StorageClass.
- Add example spec files

Handle code review comments.

- Modified READMEs to incorporate to suggestions.
- Add a test for ReadWriteMany access mode.
- Use util.UnmountPath in TearDown.
- Add ReadOnly flag to PortworxVolumeSource
- Use hostname:port instead of unix sockets
- Delete the mount dir in TearDown.
- Fix link issue in persistentvolumes README
- In unit test check for mountpath after Setup is done.
- Add PVC Claim Name as a Portworx Volume Label

Generated code and documentation.
- Updated swagger spec
- Updated api-reference docs
- Updated generated code under pkg/api/v1

Godeps update for Portworx Volume Driver
- Adds github.com/libopenstorage/openstorage
- Adds go.pedge.io/pb/go/google/protobuf
- Updates Godep Licenses

pkg/api/validation/validation.go

@@ -511,6 +511,14 @@ func validateVolumeSource(source *api.VolumeSource, fldPath *field.Path) field.E
 			allErrs = append(allErrs, validatePhotonPersistentDiskVolumeSource(source.PhotonPersistentDisk, fldPath.Child("photonPersistentDisk"))...)
 		}
 	}
+	if source.PortworxVolume != nil {
+		if numVolumes > 0 {
+			allErrs = append(allErrs, field.Forbidden(fldPath.Child("portworxVolume"), "may not specify more than 1 volume type"))
+		} else {
+			numVolumes++
+			allErrs = append(allErrs, validatePortworxVolumeSource(source.PortworxVolume, fldPath.Child("portworxVolume"))...)
+		}
+	}
 	if source.AzureDisk != nil {
 		numVolumes++
 		allErrs = append(allErrs, validateAzureDisk(source.AzureDisk, fldPath.Child("azureDisk"))...)
@@ -979,6 +987,14 @@ func validatePhotonPersistentDiskVolumeSource(cd *api.PhotonPersistentDiskVolume
 	return allErrs
 }
 
+func validatePortworxVolumeSource(pwx *api.PortworxVolumeSource, fldPath *field.Path) field.ErrorList {
+	allErrs := field.ErrorList{}
+	if len(pwx.VolumeID) == 0 {
+		allErrs = append(allErrs, field.Required(fldPath.Child("volumeID"), ""))
+	}
+	return allErrs
+}
+
 // ValidatePersistentVolumeName checks that a name is appropriate for a
 // PersistentVolumeName object.
 var ValidatePersistentVolumeName = NameIsDNSSubdomain
@@ -1138,6 +1154,14 @@ func ValidatePersistentVolume(pv *api.PersistentVolume) field.ErrorList {
 			allErrs = append(allErrs, validatePhotonPersistentDiskVolumeSource(pv.Spec.PhotonPersistentDisk, specPath.Child("photonPersistentDisk"))...)
 		}
 	}
+	if pv.Spec.PortworxVolume != nil {
+		if numVolumes > 0 {
+			allErrs = append(allErrs, field.Forbidden(specPath.Child("portworxVolume"), "may not specify more than 1 volume type"))
+		} else {
+			numVolumes++
+			allErrs = append(allErrs, validatePortworxVolumeSource(pv.Spec.PortworxVolume, specPath.Child("portworxVolume"))...)
+		}
+	}
 	if pv.Spec.AzureDisk != nil {
 		numVolumes++
 		allErrs = append(allErrs, validateAzureDisk(pv.Spec.AzureDisk, specPath.Child("azureDisk"))...)