`lib/swipe-stack-0.1.js`: removing some cruft (unneeded code inherited from the library this was forked from); fixed a bug that affected stacks with only one item

`app.jsx`: minor

`chooseScreen.js`: fixed test for pubSubDomain

`swipeStackSlider.js`: fixed to only bind to the current slider (was overwriting handlers on all sliders)

`gatherings.jsx`: show `matchOverlay` when RSVPing (to see if they want to invite others or continue browsing gatherings); minor changes to accommodate changes to `lib/swipe-stack-0.1.js`

`heroes`: minor changes to accommodate changes to `lib/swipe-stack-0.1.js`