Adding Initialize() to create a new container.

Docker-DCO-1.1-Signed-off-by: Victor Marmol <vmarmol@google.com> (github: vmarmol)

factory.go

@@ -0,0 +1,17 @@
+package libcontainer
+
+type Factory interface {
+	// Initializes a new container with the specified ID and config. The ID is a user-provided
+	// opaque identifier. Starts an init process with the initialProcess config inside the new
+	// container.
+	//
+	// Returns the new container and the PID of the new init inside the container.
+	// The caller must reap this PID.
+	//
+	// Errors: ID already exists,
+	//         config or initialConfig is invalid,
+	//         system error.
+	//
+	// On error, any partially created container parts are cleaned up (the operation is atomic).
+	Initialize(id string, config *Config, initialProcess *ProcessConfig) (*Container, int, error)
+}