cmd/swarm: trim trailing slash from bzzapi url

cmd/swarm/upload.go

@@ -36,7 +36,7 @@ import (
 func upload(ctx *cli.Context) {
 	args := ctx.Args()
 	var (
-		bzzapi       = ctx.GlobalString(SwarmApiFlag.Name)
+		bzzapi       = strings.TrimRight(ctx.GlobalString(SwarmApiFlag.Name), "/")
 		recursive    = ctx.GlobalBool(SwarmRecursiveUploadFlag.Name)
 		wantManifest = ctx.GlobalBoolT(SwarmWantManifestFlag.Name)
 	)