Whitespace is not consistent across files

[geoffp]

We want to get our whitespace and code formatting situation in order, so I propose we:

• Add .eslintrc and .editorconfig and document their integration into editors
• Develop a consensus on what those rules should be: the first version will be a proposal
• Remove IIFE closures from builder/*.js modules
• Reformat javascript files to pass lint
• Optional: add a JS linting step into gulp/grunt
• test & document the use of editorconfig/eslintrc files, perhaps just inside .github/CONTRIBUTING.md?

Edit: @bmuenzenmeyer edited to merge lists with the duplicate issue #264