Migrate Sirupsen to sirupsen.

vendor/github.com/docker/distribution/context/doc.go

@@ -64,7 +64,7 @@
 // Note that this only affects the new context, the previous context, with the
 // version field, can be used independently. Put another way, the new logger,
 // added to the request context, is unique to that context and can have
-// request scoped varaibles.
+// request scoped variables.
 //
 // HTTP Requests
 //

vendor/github.com/docker/distribution/context/http.go

@@ -8,9 +8,9 @@ import (
 	"sync"
 	"time"
 
-	log "github.com/Sirupsen/logrus"
 	"github.com/docker/distribution/uuid"
 	"github.com/gorilla/mux"
+	log "github.com/sirupsen/logrus"
 )
 
 // Common errors used with this package.

vendor/github.com/docker/distribution/context/logger.go

@@ -3,7 +3,7 @@ package context
 import (
 	"fmt"
 
-	"github.com/Sirupsen/logrus"
+	"github.com/sirupsen/logrus"
 	"runtime"
 )