FEATURE: Support privileged containers in a pod

Add a Privileged field to containers in a pod, in order to facilitate pods
performing administrative tasks such as builds via Docker-in-Docker.

Discussion: https://github.com/GoogleCloudPlatform/kubernetes/issues/391

pkg/api/types.go

@@ -195,6 +195,8 @@ type Container struct {
 	VolumeMounts  []VolumeMount  `yaml:"volumeMounts,omitempty" json:"volumeMounts,omitempty"`
 	LivenessProbe *LivenessProbe `yaml:"livenessProbe,omitempty" json:"livenessProbe,omitempty"`
 	Lifecycle     *Lifecycle     `yaml:"lifecycle,omitempty" json:"lifecycle,omitempty"`
+	// Optional: Default to false.
+	Privileged bool `json:"privileged,omitempty" yaml:"privileged,omitempty"`
 }
 
 // Handler defines a specific action that should be taken