Update cli imports to using local package

Also, rename a bunch of variable to not *shadow* the `opts` package
name.

Signed-off-by: Vincent Demeester <vincent@sbr.pm>

cli/command/stack/common.go

@@ -1,14 +1,13 @@
 package stack
 
 import (
-	"golang.org/x/net/context"
-
 	"github.com/docker/cli/cli/compose/convert"
+	"github.com/docker/cli/opts"
 	"github.com/docker/docker/api/types"
 	"github.com/docker/docker/api/types/filters"
 	"github.com/docker/docker/api/types/swarm"
 	"github.com/docker/docker/client"
-	"github.com/docker/docker/opts"
+	"golang.org/x/net/context"
 )
 
 func getStackFilter(namespace string) filters.Args {