fs: Cleanup Golang errors to be called 'e' and probe to be called as 'err'

- Replace the ACL checks back, remove them when bucket
  policy is implemented.
- Move FTW (File Tree Walk) into ioutils package.

main.go

@@ -19,7 +19,6 @@ package main
 import (
 	"fmt"
 	"os"
-	"os/user"
 	"runtime"
 	"strconv"
 
@@ -55,12 +54,6 @@ func init() {
 	// Check if minio was compiled using a supported version of Golang.
 	checkGolangRuntimeVersion()
 
-	// Check for the environment early on and gracefuly report.
-	_, err := user.Current()
-	if err != nil {
-
-	}
-
 	if os.Getenv("DOCKERIMAGE") == "1" {
 		// the further checks are ignored for docker image
 		return