Extract cgroups pkg.

Initial move before enhancing cgroups package.

Docker-DCO-1.1-Signed-off-by: Paul Nasrat <pnasrat@gmail.com> (github: pnasrat)

execdriver/driver.go

@@ -2,7 +2,7 @@ package execdriver
 
 import (
 	"errors"
-	"github.com/dotcloud/docker/cgroups"
+	"github.com/dotcloud/docker/pkg/cgroups"
 	"os/exec"
 	"syscall"
 )

execdriver/lxc/lxc_template.go

@@ -1,7 +1,7 @@
 package lxc
 
 import (
-	"github.com/dotcloud/docker/cgroups"
+	"github.com/dotcloud/docker/pkg/cgroups"
 	"strings"
 	"text/template"
 )

execdriver/lxc/lxc_template_unit_test.go

@@ -3,8 +3,8 @@ package lxc
 import (
 	"bufio"
 	"fmt"
-	"github.com/dotcloud/docker/cgroups"
 	"github.com/dotcloud/docker/execdriver"
+	"github.com/dotcloud/docker/pkg/cgroups"
 	"io/ioutil"
 	"math/rand"
 	"os"