provider/aws: Support Import of `aws_db_option_group`

```
make testacc TEST=./builtin/providers/aws
TESTARGS='-run=TestAccAWSDBOptionGroup_'
==> Checking that code complies with gofmt requirements...
go generate $(go list ./... | grep -v /vendor/)
TF_ACC=1 go test ./builtin/providers/aws -v
-run=TestAccAWSDBOptionGroup_ -timeout 120m
=== RUN   TestAccAWSDBOptionGroup_importBasic
--- PASS: TestAccAWSDBOptionGroup_importBasic (22.98s)
=== RUN   TestAccAWSDBOptionGroup_basic
--- PASS: TestAccAWSDBOptionGroup_basic (22.54s)
=== RUN   TestAccAWSDBOptionGroup_OptionSettings
--- PASS: TestAccAWSDBOptionGroup_OptionSettings (38.62s)
=== RUN   TestAccAWSDBOptionGroup_sqlServerOptionsUpdate
--- PASS: TestAccAWSDBOptionGroup_sqlServerOptionsUpdate (37.64s)
=== RUN   TestAccAWSDBOptionGroup_multipleOptions
--- PASS: TestAccAWSDBOptionGroup_multipleOptions (24.32s)
PASS
ok      github.com/hashicorp/terraform/builtin/providers/aws    146.123s
```

builtin/providers/aws/import_aws_db_option_group_test.go

@@ -0,0 +1,31 @@
+package aws
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/hashicorp/terraform/helper/acctest"
+	"github.com/hashicorp/terraform/helper/resource"
+)
+
+func TestAccAWSDBOptionGroup_importBasic(t *testing.T) {
+	resourceName := "aws_db_option_group.bar"
+	rName := fmt.Sprintf("option-group-test-terraform-%s", acctest.RandString(5))
+
+	resource.Test(t, resource.TestCase{
+		PreCheck:     func() { testAccPreCheck(t) },
+		Providers:    testAccProviders,
+		CheckDestroy: testAccCheckAWSDBOptionGroupDestroy,
+		Steps: []resource.TestStep{
+			resource.TestStep{
+				Config: testAccAWSDBOptionGroupBasicConfig(rName),
+			},
+
+			resource.TestStep{
+				ResourceName:      resourceName,
+				ImportState:       true,
+				ImportStateVerify: true,
+			},
+		},
+	})
+}

builtin/providers/aws/resource_aws_db_option_group.go

@@ -19,6 +19,9 @@ func resourceAwsDbOptionGroup() *schema.Resource {
 		Read:   resourceAwsDbOptionGroupRead,
 		Update: resourceAwsDbOptionGroupUpdate,
 		Delete: resourceAwsDbOptionGroupDelete,
+		Importer: &schema.ResourceImporter{
+			State: schema.ImportStatePassthrough,
+		},
 
 		Schema: map[string]*schema.Schema{
 			"arn": &schema.Schema{
@@ -125,7 +128,7 @@ func resourceAwsDbOptionGroupCreate(d *schema.ResourceData, meta interface{}) er
 func resourceAwsDbOptionGroupRead(d *schema.ResourceData, meta interface{}) error {
 	rdsconn := meta.(*AWSClient).rdsconn
 	params := &rds.DescribeOptionGroupsInput{
-		OptionGroupName: aws.String(d.Get("name").(string)),
+		OptionGroupName: aws.String(d.Id()),
 	}
 
 	log.Printf("[DEBUG] Describe DB Option Group: %#v", params)
@@ -143,7 +146,7 @@ func resourceAwsDbOptionGroupRead(d *schema.ResourceData, meta interface{}) erro
 
 	var option *rds.OptionGroup
 	for _, ogl := range options.OptionGroupsList {
-		if *ogl.OptionGroupName == d.Get("name").(string) {
+		if *ogl.OptionGroupName == d.Id() {
 			option = ogl
 			break
 		}
@@ -153,6 +156,7 @@ func resourceAwsDbOptionGroupRead(d *schema.ResourceData, meta interface{}) erro
 		return fmt.Errorf("Unable to find Option Group: %#v", options.OptionGroupsList)
 	}
 
+	d.Set("name", option.OptionGroupName)
 	d.Set("major_engine_version", option.MajorEngineVersion)
 	d.Set("engine_name", option.EngineName)
 	d.Set("option_group_description", option.OptionGroupDescription)