Webpack dev server (#902)

* Initial webpack config. Moving to ES6 modules. Some module cleanup.

* WIP

* WIP

* Removing commented out code.

* Removing old deps.

* Removing the build script (used for testing).

* Working tests.

* Switching to node api over cli.

* Updating per comments. Still need to fix server.js to properly run the selenium tests.

* Cleaning up the config.

* More cleanup.

* Bringing back server.js for selenium tests.

* Bringing back old dependencies.

* Adding back eslint rules for webpack config. Final cleanup for webpack config.

* Pointing to correct pre-existing module versions. Adding some extra logic to server.js to ensure it gets transpiled properly.

* Getting make build to work again. Updating package.json with some shortcut scripts.

* Resolving conflict.

* Reverting back to commonjs modules.

* Removing extra spaces in babelrc

katex.js

@@ -43,6 +43,7 @@ if (typeof document !== "undefined") {
     }
 }
 
+
 /**
  * Parse and build an expression, and return the markup for that.
  */
@@ -61,7 +62,8 @@ const generateParseTree = function(expression, options) {
     return parseTree(expression, settings);
 };
 
-module.exports = {
+
+const katex = {
     render: render,
     renderToString: renderToString,
     /**
@@ -72,3 +74,5 @@ module.exports = {
     __parse: generateParseTree,
     ParseError: ParseError,
 };
+
+export default katex;