Add NewContainer and Delete container support

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

client_test.go

@@ -1,6 +1,9 @@
 package containerd
 
-import "testing"
+import (
+	"context"
+	"testing"
+)
 
 const defaultAddress = "/run/containerd/containerd.sock"
 
@@ -16,3 +19,38 @@ func TestNewClient(t *testing.T) {
 		t.Errorf("client closed returned errror %v", err)
 	}
 }
+
+func TestNewContainer(t *testing.T) {
+	client, err := New(defaultAddress)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer client.Close()
+
+	id := "test"
+	spec, err := GenerateSpec(WithHostname(id))
+	if err != nil {
+		t.Error(err)
+		return
+	}
+	container, err := client.NewContainer(context.Background(), id, spec)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+	if container.ID() != id {
+		t.Errorf("expected container id %q but received %q", id, container.ID())
+	}
+	if spec, err = container.Spec(); err != nil {
+		t.Error(err)
+		return
+	}
+	if spec.Hostname != id {
+		t.Errorf("expected spec hostname id %q but received %q", id, container.ID())
+		return
+	}
+	if err := container.Delete(context.Background()); err != nil {
+		t.Error(err)
+		return
+	}
+}