Move registry package out of repo root

Since the repo is no longer just the registry, we are moving the registry web
application package out of the repo root into a sub-package. We may break down
the registry package further to separate webapp components and bring the client
package under it. This change accomplishes the task of freeing up the repo root
for a distribution-oriented package. A stub doc.go file is left in place to
declare intent.

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

registry/util.go

@@ -0,0 +1,27 @@
+package registry
+
+import (
+	"net/http"
+	"reflect"
+	"runtime"
+
+	"github.com/gorilla/handlers"
+)
+
+// functionName returns the name of the function fn.
+func functionName(fn interface{}) string {
+	return runtime.FuncForPC(reflect.ValueOf(fn).Pointer()).Name()
+}
+
+// resolveHandlerName attempts to resolve a nice, pretty name for the passed
+// in handler.
+func resolveHandlerName(method string, handler http.Handler) string {
+	switch v := handler.(type) {
+	case handlers.MethodHandler:
+		return functionName(v[method])
+	case http.HandlerFunc:
+		return functionName(v)
+	default:
+		return functionName(handler.ServeHTTP)
+	}
+}