Move registry api definitions under registry package

Signed-off-by: Stephen J Day <stephen.day@docker.com>

docs/handlers/app.go

@@ -7,7 +7,7 @@ import (
 	"os"
 
 	"code.google.com/p/go-uuid/uuid"
-	"github.com/docker/distribution/api/v2"
+	"github.com/docker/distribution/registry/api/v2"
 	"github.com/docker/distribution/auth"
 	"github.com/docker/distribution/configuration"
 	ctxu "github.com/docker/distribution/context"