Add "sourceType" : "module" into parserOptions and remove 'use strict'

[owennicol]

If we add "sourceType" : "module" into the eslintrc so that our "parserOptions" config looks like this:

"parserOptions": {
    "ecmaVersion": 6,
    "sourceType": "module",
    "ecmaFeatures": {
      "jsx": true
    }
  },

This would allow us to remove 'use strict' from all of our modules and, in the case of our themeBlueprint repo, save us 7215 characters.

http://stackoverflow.com/a/31685340