added refresh for patients on accept invitation

@nicolashery ready for review. Can you look at line 35 and 50 in invitation.js and suggest what to do with the potential error
Sorry, I probably haven't made it clear in the documentation, but nothing besides the main `App` components is supposed to call `api.js` directly (allows for testing etc.).

Instead, pass handlers as props to the components, for example:

```javascript
{
  onDismiss: React.PropTypes.func
}
```

See other components for inspiration :)