[Doppins] Upgrade dependencies

[doppins-bot]

Hi, and thank you for trying out Doppins.

This initial pull request upgrades all your dependency ranges to the latest
available version. From now on any new dependency releases will result in a pull
request to your repository, submitted in real-time.

Make sure that it doesn't break anything, and happy merging!

The upgraded dependencies are:

---

• gulp-nodemon from 2.0.4 to 2.0.6
• cookie-parser from 1.4.0 to 1.4.1
• raven from 0.8.1 to 0.10.0
• lodash from 3.10.1 to 4.3.0
• redis from 2.3.0 to 2.4.2
• express from 4.13.3 to 4.13.4
• socket.io from 1.3.7 to 1.4.5
• bower from 1.6.5 to 1.7.7
• body-parser from 1.14.1 to 1.15.0
• request from 2.65.0 to 2.69.0
• stylus from 0.52.4 to 0.53.0
• bluebird from 3.0.2 to 3.2.2
• slack-notify from 0.1.5 to 0.1.6
• eslint-config-airbnb from ^1.0.0 to ^5.0.0
• chai from 3.4.0 to 3.5.0
• chai-as-promised from 5.1.0 to 5.2.0
• rewire from 2.5.0 to 2.5.1
• mocha from 2.3.3 to 2.4.5
• should from 7.1.1 to 8.2.2
• istanbul from 0.4.0 to 0.4.2