Organize files and clean up the project root

[beechnut]

Our project root has a lot cluttering it up. I suspect we can organize and/or remove a good deal.

Here's a list of proposed changes, which may change upon further investigation.

Remember Chesterton's Fence! Some things are probably there for a reason. (But some things might actually be unused.)

• Move binaries (serve*, build) to a bin/ folder or remove, and update invocations (e.g. in package.json)
• Move non-binary (lol) scripts (docker_entrypoint.rb etc) to script/
• Move linters / rc files (eslintrc, scss-lint) to a directory and update invocations to match.
• Get rid of killport — there should be no need to kill ports
• Remove check_images.rb (assuming it's safe to do so)
• Move bonus configs to /config and update references to it in scripts
• Change owner information — Greg Boone and other alums are listed as owner/team
• Move favicon.ico. Guessing we don't need it there, because _site is where the published files live, and they're handled by favicon.yml.
• 404.html looks important, but it's "for AccessLint purposes only". So, we probably don't need that in our project root either.