updated to skeletal tracking beta 2.0.0+15464 (includes template fix)

This will update the project to the Leap Motion skeletal tracking beta version 2.0.0+15464 (mac and windows).

If you'd rather have a third "beta" branch in your repo to leave "dev" for testing updates to the latest stable non-beta Leap Motion SDK, just make that branch and I'll PR to it instead.

Fixes #8