Preset cubes dropdown

[benjaminpwagner]

Adds a dropdown next to the cube list textarea. Fills textarea upon selection (Using global App.state)

Also added axios and babel-polyfill - updated webpack config to allow for async/await usage on the client side.

Fixes #3

update: fixes clean-webpack-plugin error with v2

[HerveH44]

Hey, that seems awesome. Though I have couple questions:

• why axios and not use builtin "fetch" ?
• why remove webpack clean plugin ? You don't think it's safer to delete all previous builds before making a new one?
  -The preset cubes selects/options maybe could have been a "Select" component? I feel that you have all the informations to create our custom Select, it's easier to read I think (under public/src/utils.jsx)
• Could we sanitize the elements we send back from the "cubes" API? I know it sounds silly but I just read about this kind of things...
• What is the use of babel/polyfill?