* Create a separate entry point for webpack

Created a webpack entry point for KaTeX, which imports katex.less. As
flow[1] and jest[2] doesn't support CSS modules natively, a separate
entry point is used and it is not flowtyped.

[1] https://gist.github.com/lambdahands/d19e0da96285b749f0ef
[2] https://facebook.github.io/jest/docs/en/webpack.html

* Use webpack to build files

* Made webpack.config.js export valid webpack configuration
* Use:
browserify -> webpack
babelify -> babel-loader
UglifyJS CLI -> UglifyJsPlugin
Less CLI -> less-loader
cleancss -> cssnano in css-loader
build/fonts -> file-loader
* Inline CSS(Less) using style-loader and export them using
ExtractTextPlugin
* Add `watch` npm script calling `webpack --watch`

* Improve local testing(webpack-dev-server)

* Made webpackDevServer export a valid webpack configuration
* Compile Less and inline CSS using less-loader and style-loader
* Instead of copying files serve files from /static and use file-loader
* Remove old server.js and its dependencies

* Use webpack-dev-server in Screenshotter

* Include contrib in webpack-dev-server

+ Moved common configurations to webpack.common.js

* Rename webpackDevServer.js to webpack.dev...

to be consistent, avoid confusion with webpack-dev-server and follow
webpack configuration naming convention.

* Remove unnecessary conditional output.path

* Use map instead of reduce

+ Add comments regarding function arguments

* Remove unnecessary mkdir and clean build/* before build

* Use katex as external dependency instead of global variable in contrib

Fixes #692.

* Unblock codes as they are built as a module

* Update package-lock.json

* Add comments regarding devServer option

* Lint renamed webpack.dev.js

a0d8b33

* Export ES6 module and expose its default export

* Revert "Browserify hotfix (#1057)"

This reverts commit f6b5091.

* Enables colors on the console when running the dev server in Screenshotter

* Add context to webpack configuration

Allows webpack to be run from other directories

* Move `rm -rf build/*` to npm scripts

* Check dependencies before build

* Move UglifyJsPlugin into config creation

* Let webpack handle ES6 modules

Do not transform modules to commonjs in Babel. However Jest doesn't not
support ES6 modules, so transfrom modules to commonjs when NODE_ENV is
`test`.

* Add documentation on testing in IE 9 and 10 using webpack-dev-server

Changed version range to include IE-compatible version