webpack cleanup

[stmoreau]

In webpack.config.js I created this regex /\.(png|jpg|gif|svg)$/ to test all files ending in png, jpg, gif, or svg and pass them through the url-loader instead of having to test each one of them separately.

• Better use of webpack
• Less lines of code
• Increased readability

Thank you for accepting my PR in advance :bowtie:

[kale-stew]

Apologies for the delay, but I'm going to close this PR for relevancy. It appears to contain a number of changes beyond your webpack fix, from a much earlier commit, and I don't want to merge a regression. If you would like to open a new PR with your isolated changes, we would welcome it!