In order to build this project, from the root directory type $ npm run build
In order to test that the webpack is built correctly, navigate to the
build_webpack folder with $ cd build_webpack and then open index.html with
$ open index.html.
TLDR; $ npm run build && cd build_webpack && open index.html
EthTipJar.deployed().then(function(res){ETJ = EthTipJar.at(res.address)})