Use 6to5 to compile ES6 code.
Renamed bundle to app.js
Add 6to5 npm module compatibility option (--modules commonInterop).
Refactor in ES6 let, const and modules features.
More refactoring to ES6.
Simplified dispatch actions and droped redundant Model.remove().
Rename LocalStorage sync factory function and start with lower case (it's not a constructor function).
Bump version number.
Upgrade npm package versions.