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
If you pass an `onDismiss` handler as a props, which calls a `handleInviteDismiss()` in the main `App` component, you won't need this anymore. The app will just remove the invite from it's `state.invites` list, and the re-render that's triggered will make sure the notification disappears from the UI.