Open menu on right

Hi,
I have tried to open the menu on the right but it seems do not work.

```
<ion-header>

  <ion-navbar>
    <ion-buttons start>
      <button ion-button menuToggle right>
        <ion-icon name="menu"></ion-icon>
      </button>
    </ion-buttons>
    <ion-title>Posts</ion-title>
  </ion-navbar>

</ion-header>
``` 