Use external dependencies rather than including them in repo

[SpangleLabs]

Spinning off from #3, not solved in #8.

This project has 5 dependencies, with varying levels of ease that they could become externally managed ones:

• FileSaver.js: No local changes, easy to switch to external package: https://www.npmjs.com/package/file-saver
• moment.js: No local changes, easy to switch to external package: https://www.npmjs.com/package/moment
• md5.js: Very old, but should be easy to swap for an off-the-shelf solution. It's only used for random colour generation anyway
• Chart.js: Quite a few changes. Would be very good to use external dependency, but might be a struggle.
• timeline.js: Basically rewritten. Maybe pull it in here, or something? Check licenses and such for sure.