add eslint and apply initial rules

[vutran]

This PR adds eslint (#5) with some initial rules along with an .editorconfig file for editor consistency (#20).

I know I mentioned to utilized webpack's rules but it would require a lot of reformatting of the white-space so I figured keeping the current 2-space indents.

Initial General Ruleset:

• 2-space indentation
• Semicolons
• Comma-dangle for multiple objects for better git diffs
• Use single quotes for strings (a few were using double-quotes so applying this for consistency)

To run:

$ npm run lint

[TheLarkInn]

Looks great thank you so much!!