func (c ByCreated) Less(i, j int) bool {
	t1, err := time.Parse(time.RFC3339Nano, c[i].containerInfo.Created)
	if err != nil {
		t1 = time.Now()
	}
	t2, _ := time.Parse(time.RFC3339Nano, c[j].containerInfo.Created)
	if err != nil {
		t1 = time.Now()
	}
	return t1.Before(t2)
}
Less will compare two elements (identified by index) in the Container
list by created-date.
package container
import (
	"time"
	"github.com/pkg/errors"
)
type ByCreated []Container
func (c ByCreated) Len() int      { return len(c) }
func (c ByCreated) Swap(i, j int) { c[i], c[j] = c[j], c[i] }