listObjects: Cleanup and naming conventions.

- Marker should be escaped outside in handlers.

- Delimiter should be handled outside in handlers.

- Add missing comments and change the function names.

- Handle case of 'maxKeys' when its set to '0', its a valid

  case and should be treated as such.

object-handlers.go

@@ -34,12 +34,7 @@ import (
 	"github.com/minio/minio/pkg/probe"
 )
 
-const (
-	maxPartsList = 1000
-)
-
-// supportedGetReqParams - supported request parameters for GET
-// presigned request.
+// supportedGetReqParams - supported request parameters for GET presigned request.
 var supportedGetReqParams = map[string]string{
 	"response-expires":             "Expires",
 	"response-content-type":        "Content-Type",