Ignore this file. It only exists because git refuses to push empty directories to a remote server. .gitkeep is an unofficial convention that has emerged as a workaround for people who don't discriminate against empty directories.
Want to see for yourself?
An example of this file can be found in our sample app repo, here.
The Sails framework is maintained by a web & mobile studio in Austin, TX, with the help of our contributors. We created Sails in 2012 to assist us on Node.js projects. Naturally we open-sourced it. We hope it makes your life a little bit easier!