temp: omit publicPath from webpack.config.js

[justinhynes]

Temporary change that is a test fix for APER-2210. I read that if publicPath is set in a webpack config then django-webpack-loader will use publicPath over the static URL settings. I think this could be the source of the problem with some of our assets being accessed at an incorrect URL.

I'm making this change based on a conversation here: django-webpack/django-webpack-loader#107, specifically:

@mik3y Preferring publicPath over django's storage is a feature and the only way to give preference to django's storage right now is to omit publicPath from your webpack config like you correctly pointed out.