Consider adding an .editorconfig to enforce aspects of the style guide

[iamgollum]

When I was working on issue #1202, I noticed in my PR that the format was off. I went to check the repo and noticed there was no .editorconfig. This can help standardize styling across os / contributors.

https://github.com/apache/couchdb-fauxton/blob/master/styleguide.md

Aka for a base:

root = true

[*]
indent_style = space
indent_size = 2

[popojargo]

I would be +1 on this. We already have eslint for code formatting but a .editorconfig would also helps being consistent in the different files.