chore: Add Greenkeeper support for npm 5.x's `package-lock.json` file.
chore: Add Greenkeeper support for npm 5.x's `package-lock.json` file.

GaryJones/stylelint-config-wordpress,ntwb/stylelint-config-wordpress,stylelint/stylelint-config-wordpress,WordPress-Coding-Standards/stylelint-config-wordpress