func NewHTTPGetter(URL, CertFile, KeyFile, CAFile string) (*HttpGetter, error) {
	var client HttpGetter
	tr := &http.Transport{
		DisableCompression: true,
		Proxy:              http.ProxyFromEnvironment,
	}
	if (CertFile != "" && KeyFile != "") || CAFile != "" {
		tlsConf, err := tlsutil.NewTLSConfig(URL, CertFile, KeyFile, CAFile)
		if err != nil {
			return &client, fmt.Errorf("can't create TLS config: %s", err.Error())
		}
		tr.TLSClientConfig = tlsConf
	}
	client.client = &http.Client{Transport: tr}
	return &client, nil
}
NewHTTPGetter constructs a valid http/https client as HttpGetter
package getter
import (
	"bytes"
	"fmt"
	"io"
	"net/http"
	"strings"
	"k8s.io/helm/pkg/tlsutil"
	"k8s.io/helm/pkg/version"
)
type HttpGetter struct {  
	client   *http.Client
	username string
	password string
}
func (g *HttpGetter) SetCredentials(username, password string) {
	g.username = username
	g.password = password
}
func (g *HttpGetter) Get(href string) (*bytes.Buffer, error) {
	return g.get(href)
}
func (g *HttpGetter) get(href string) (*bytes.Buffer, error) {
	buf := bytes.NewBuffer(nil)
	req, err := http.NewRequest("GET", href, nil)
	if err != nil {
		return buf, err
	}
	req.Header.Set("User-Agent", "Helm/"+strings.TrimPrefix(version.GetVersion(), "v"))
	if g.username != "" && g.password != "" {
		req.SetBasicAuth(g.username, g.password)
	}
	resp, err := g.client.Do(req)
	if err != nil {
		return buf, err
	}
	if resp.StatusCode != 200 {
		return buf, fmt.Errorf("Failed to fetch %s : %s", href, resp.Status)
	}
	_, err = io.Copy(buf, resp.Body)
	resp.Body.Close()
	return buf, err
}
func newHTTPGetter(URL, CertFile, KeyFile, CAFile string) (Getter, error) {
	return NewHTTPGetter(URL, CertFile, KeyFile, CAFile)
}