Fix module exports

[anilpixel]

When I use your progress bar with Jest(babel-jest for loader), babel-jest can't load this module: I think the reason is in lib/ProgressBar.js

exports.default = ProgressBar;
module.exports = exports['default']; 

it's NOT a standard babel6 compiled result for ES Module, because .babelrc use babel-plugin-add-module-exports.

So I remove babel-plugin-add-module-exports from .babelrc, and rebuild it.

PS: I'm sorry disabled eslint-rule: jsx-a11y/no-static-element-interactions and my poor Engilsh.