Move raw cgroups into fs package (filesystem)

Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)

pkg/cgroups/utils.go

@@ -3,9 +3,7 @@ package cgroups
 import (
 	"bufio"
 	"io"
-	"io/ioutil"
 	"os"
-	"path/filepath"
 	"strings"
 
 	"github.com/dotcloud/docker/pkg/mount"
@@ -67,7 +65,3 @@ func parseCgroupFile(subsystem string, r io.Reader) (string, error) {
 	}
 	return "", ErrNotFound
 }
-
-func writeFile(dir, file, data string) error {
-	return ioutil.WriteFile(filepath.Join(dir, file), []byte(data), 0700)
-}