Buttplug Integration with Yiffspot

[qdot]

This PR contains all of the code for basic Buttplug (https://github.com/metafetish/buttplug-js) integration with Yiffspot. The first 6 commits are project preparation, with the final commit (f881310) containing all of the integration code.

All patch code has been manually tested, though probably not well.

Possible issues:

• The Buttplug panel on the sidebar takes up a surprising amount of room, and I'm not sure how many people are actually going to use this. Still wondering if this should maybe ship collapsed by default, with a click event to uncollapse it?
• This balloons the project to something like 4.5x its current size. On initial network transfer with caching disabled, current yiffspot sends ~208kb. This patch expands that to ~948kb due to dependencies. May be worth looking into gzip'ing before things hit the line on the express side. :(
• We only support vibrating devices for the moment, and the UI isn't real clear about that.
• There's a good chance we may opaquely drop some errors. I tried to test everything but manual QA is hard. :)

PR build is up and running at https://teledildonic-yiffspot.glitch.me/ if you want to test the patch without rolling your own server.

Fixes #37