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/context.go

@@ -0,0 +1,32 @@
+package registry
+
+import (
+	"github.com/Sirupsen/logrus"
+	"github.com/docker/distribution/api/v2"
+)
+
+// Context should contain the request specific context for use in across
+// handlers. Resources that don't need to be shared across handlers should not
+// be on this object.
+type Context struct {
+	// App points to the application structure that created this context.
+	*App
+
+	// Name is the prefix for the current request. Corresponds to the
+	// namespace/repository associated with the image.
+	Name string
+
+	// Errors is a collection of errors encountered during the request to be
+	// returned to the client API. If errors are added to the collection, the
+	// handler *must not* start the response via http.ResponseWriter.
+	Errors v2.Errors
+
+	// vars contains the extracted gorilla/mux variables that can be used for
+	// assignment.
+	vars map[string]string
+
+	// log provides a context specific logger.
+	log *logrus.Entry
+
+	urlBuilder *v2.URLBuilder
+}