Translation files not served from endpoints other than "/"

[catarak]

Nature of issue?

• Found a bug

Details about the bug:

• Web browser and version: Chrome
• Operating System: Mac OSX
• Steps to reproduce this bug:

1. Navigate to any endpoint that is not /, e.g. https://editor.p5js.org/cassie/sketches/Wyu-U_0zn
2. Look at all of the requests that the website makes
3. Notice that the translation.json files return 404

cc @oruburos && @andrewn

Since this is a super quick fix (just changing i18n.js#L10) and and is fairly critical, I'm just going to fix this 😄

[andrewn]

@catarak Sorry about this, I should have spotted that. Thanks for fixing!