Support for Mobile Gestures

I would love to see some kind of support for mobile devices for gestures. There would probably need to be different options for what kind of gestures you support, if any, and the implementation would need to not get too weighty. The gestures I'd love to see are:

1. ~swipe open~
2. ~swipe closed~
3. pan opened
4. pan closed
5. menu grab area threshold

The issue names no files or tests. Start by inspecting the ember-burger-menu component and its existing interaction entry points, then clarify which gestures and menu grab threshold are in scope. Done should mean an agreed set of mobile gestures works without making the implementation unnecessarily heavy.

索引モデルが issue の本文から書いたものです。