You'll need:
- Firefox - https://addons.mozilla.org/en-US/firefox/addon/greasemonkey/
- Chrome - https://chrome.google.com/webstore/detail/tampermonkey/dhdgffkkebhmkfjojejmpbldmpobfkfo
- Safari/IE/Opera - No idea, look for greasemonkey-compatible addon/extension
Then, click on the following link and install the script: https://gist.github.com/VictorBjelkholm/5eb6502328bd2ed902ce5293ad80f33c/raw/136beeb89646e8eb81f56b24f03b60c1512c2885/is-private.user.js