Set up bundling

[calebeby]

Closes #44

Run rm -rf dist && npm run build and then check that the built files in dist work:

./index.js https://cloudfour.com

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[spaceninja]

Code looks good and seems to work as described (I had to abort the test because it was taking too long on my super slow connection, but I could see that the command was running, and scanning URLs on cloudfour.com)