migrate reference github.com/distribution/reference

The "reference" package was moved to a separate module, which was extracted
from https://github.com/distribution/distribution/commit/b9b19409cf458dcb9e1253ff44ba75bd0620faa6

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

cli/command/formatter/container.go

@@ -7,7 +7,7 @@ import (
 	"strings"
 	"time"
 
-	"github.com/docker/distribution/reference"
+	"github.com/distribution/reference"
 	"github.com/docker/docker/api/types"
 	"github.com/docker/docker/pkg/stringid"
 	"github.com/docker/go-units"

cli/command/formatter/disk_usage.go

@@ -7,7 +7,7 @@ import (
 	"strings"
 	"text/template"
 
-	"github.com/docker/distribution/reference"
+	"github.com/distribution/reference"
 	"github.com/docker/docker/api/types"
 	"github.com/docker/docker/api/types/volume"
 	units "github.com/docker/go-units"

cli/command/formatter/image.go

@@ -4,7 +4,7 @@ import (
 	"fmt"
 	"time"
 
-	"github.com/docker/distribution/reference"
+	"github.com/distribution/reference"
 	"github.com/docker/docker/api/types"
 	"github.com/docker/docker/pkg/stringid"
 	units "github.com/docker/go-units"