Convert imports to ES6 from CommonJS

This is needed because `require()` means something different in webpack - it ends up importing the module as something we didn't expect (and is occasionally async)

src/VelocityBounce.js

@@ -1,4 +1,4 @@
-const Velocity = require('velocity-animate');
+import Velocity from "velocity-animate";
 
 // courtesy of https://github.com/julianshapiro/velocity/issues/283
 // We only use easeOutBounce (easeInBounce is just sort of nonsensical)