heal: Refactor heal command. (#2901)

- return errors for heal operation through rpc replies.
  - implement rotating wheel for healing status.

Fixes #2491

cmd/utils.go

@@ -163,6 +163,19 @@ func contains(stringList []string, element string) bool {
 	return false
 }
 
+// urlPathSplit - split url path into bucket and object components.
+func urlPathSplit(urlPath string) (bucketName, prefixName string) {
+	if urlPath == "" {
+		return urlPath, ""
+	}
+	urlPath = strings.TrimPrefix(urlPath, "/")
+	i := strings.Index(urlPath, "/")
+	if i != -1 {
+		return urlPath[:i], urlPath[i+1:]
+	}
+	return urlPath, ""
+}
+
 // Starts a profiler returns nil if profiler is not enabled, caller needs to handle this.
 func startProfiler(profiler string) interface {
 	Stop()