withoutMetas must return id as well.
No need to make a clone.
Add type annotation for song model id.
Replace Menuitem with span.

Menuitem is not standard.
Add fixed polymer-gestures.

https://github.com/Polymer/polymer-gestures/pull/79
Add comment.
Update for este-library 8.0.0

- este.react.Element instead of React.DOM
- este.react.Link
- No need to use este.react.Gesture directly, replaced with
este.react.Element