Update fs-extra from 3.0.1 to 4.0.2

[dependencies]

fs-extra has been updated to 4.0.2 by dependencies.io

4.0.2

• Added EOL option to writeJson* & outputJson* (via upgrade to jsonfile v4)
• Added promise support to fs.copyFile() in Node 8.5+
• Added .js extension to main field in package.json for better tooling compatibility. #485

4.0.1

Fixed

• Previously, ensureFile() & ensureFileSync() would do nothing if the path was a directory. Now, they error out for consistency with ensureDir(). #465, #466, #470

4.0.0

Changed

• BREAKING: The promisified versions of fs.read() & fs.write() now return objects. See the docs for details. #436, #449
• fs.move() now errors out when destination is a subdirectory of source. #458
• Applied upstream fixes from rimraf to fs.remove() & fs.removeSync(). #459

Fixed

• Got fs.outputJSONSync() working again; it was broken due to refactoring. #428

Also clarified the docs in a few places.