Card 1815: Add animations to right drawer

* Promote animations to beta.
* Animate right drawer, not only the center of the page when
  notifications are opened/closed.
* Use new notifications styling on mobile phones too (not only tablets).
* Animate right drawer also on phones.
* Increase animation duration to .25s (consulted with Moiz and Kaity).
* Make Overlay always emit 'hide' event. Use 'hide-button' to
  communicate with OverlayManager internally.

Change-Id: I8e67ffed1751b34ac782a1e1522706b78927c63d
Merge "Card 1815: Add animations to right drawer"