s3 backend should use Client.Delete to DeleteState

The s3.Backend was using it's own code for DeleteState, but the dynamo
entries are only handled through the RemoteClient. Have DeleteState use
a RemoteClient for delete.

backend/remote-state/s3/backend_state.go

@@ -70,20 +70,16 @@ func (b *Backend) DeleteState(name string) error {
 		return fmt.Errorf("can't delete default state")
 	}
 
-	params := &s3.DeleteObjectInput{
+	client, err := b.remoteClient(name)
-		Bucket: &b.bucketName,
-		Key:    aws.String(b.path(name)),
-	}
-
-	_, err := b.s3Client.DeleteObject(params)
 	if err != nil {
 		return err
 	}
 
-	return nil
+	return client.Delete()
 }
 
-func (b *Backend) State(name string) (state.State, error) {
+// get a remote client configured for this state
+func (b *Backend) remoteClient(name string) (*RemoteClient, error) {
 	if name == "" {
 		return nil, errors.New("missing state name")
 	}
@@ -99,8 +95,16 @@ func (b *Backend) State(name string) (state.State, error) {
 		ddbTable:             b.ddbTable,
 	}
 
-	stateMgr := &remote.State{Client: client}
+	return client, nil
+}
 
+func (b *Backend) State(name string) (state.State, error) {
+	client, err := b.remoteClient(name)
+	if err != nil {
+		return nil, err
+	}
+
+	stateMgr := &remote.State{Client: client}
 	// Check to see if this state already exists.
 	// If we're trying to force-unlock a state, we can't take the lock before
 	// fetching the state. If the state doesn't exist, we have to assume this