Fix the backend eslint config

[camjackson]

I've removed eslint from the backend build for now.

There's a weird error where this line in the backend eslint config:

extends: '../.eslintrc.yml'

ends up resolving to itself and recursing forever. I'm pretty sure it's something to do with eslint's super confusing rules for resolving relative file paths: http://eslint.org/docs/user-guide/configuring#using-a-configuration-file

[camjackson]

Possible cause: eslint/eslint#6450

This would explain why it started breaking when it was working before.

[camjackson]

I think this is long-since resolved.