minify js for production

pre-gzip js diff: 2.2 MB -> 629 KB = 29%
post-gzip js diff: 510 KB -> 223 KB = 44%

post-gzip total assets diff: 725 KB -> 446 KB = 62%

i pushed the minified version to the staging server: http://open-app.github.io/cobudget-ui/. if nobody finds an error with the minified version, i reckon we should deploy minified to our production server, seems like an easy win as initial js load already takes the longest and the API doesn't start loading until it runs the js.