* eslint: Already excludes node_modules by default.
https://eslint.org/docs/user-guide/configuring#ignoring
* eslint: Expands directories by default, much faster to
let ESLint crawl the directories while knowing what to exclude,
then to let Grunt expand **/** recursively run each file
individually.
This makes Grunt run ESLint the same way as one normally
would from the command line: `eslint .`, except without
the eslint CLI sub-process.
* eslint: Preserve the exclude for vendor via eslint config
so that it also works when running ESLint outside Grunt,
e.g. in IDEs or from the command line with extra options.
* stylelint: Ignores node_modules by default.
https://stylelint.io/user-guide/node-api/#files
Change-Id: I1a78e9d93e7666c1539bcf4a3bc50306cecf89ba