Webpack and ES6 Support + Major updates to exporting

For this release I wanted to say a HUGE thank you to all of the students who contributed as a part of Google Code-In (GCI) 2019. We wouldn't have made it here without your work; you have made lasting improvements to GCI ❤️🚀

@alexbertis, @anthony-zhou, @chen-robert, @ee9957, @tsparksh, @VladimirMikulic

v0.12.6

• Add Webpack module bundler to compile code (#512 by @VladimirMikulic)

Up to this point, we have been writing old ES5.
This change introduces Webpack, Webpack development server, Babel...
From now on, we will be able to write modern JavaScript.

v0.11.6

• Bug Fixes
  • Allow moving of images at high zoom levels (#517 by @anthony-zhou, #526)
• Enhancements
  • Add custom translation functionality for toolbar tools (#504 by @VladimirMikulic, #527)
• Features
  • Exporting! - Create customizable export UI, Add cancel export functionality, Make collection export option dynamic (#485 / #528 by @jywarren, #494 / #523 by @VladimirMikulic, #519 / #521 by @sashadev-sky)

v0.9.0

• Enhancements
  • Add tooltips for lock mode to indicate image is locked (#482 by @sashadev-sky)

v0.8.9

• API
  • Add a #setAngle method (#502 by @VladimirMikulic)
• Bug Fixes
  • Disable mouse pointer on disabled images (#507 by @tsparksh)
  • Update maxZoom to allow max value of 24 (#486 by @jywarren)
• Documentation
  • Add documentation for testing LDI (#513 by @VladimirMikulic)
• Enhancements
  • Remove unnecessary try...catch statement from #addToolbar (#490 by @alexbertis)

v0.8.8

• API
  • Update toolbar API methods #addTool, #removeTool, and #replaceTool to return meaningful values (#481 by @tsparksh)
  • Add a #getAngle method (#480 by @VladimirMikulic)
• Bug Fixes
  • Remove loading spinner after image export (#477 by @VladimirMikulic)
• Enhancements
  • Add Code of Conduct badge to README (#483 by @ee9957)
  • Add polyfill for ES6 promises (#477 by @VladimirMikulic)
  • Allow swapping between boxZoom and boxCollector (#476 by @sashadev-sky)

v0.8.6

• API
  • Add a #replaceTool method (#468 by @chen-robert)