Update ESLint to 0.17.0
I think this fixes most of our linter warnings. But it depends on this PR, so let's wait for that: https://github.com/eslint/eslint/pull/2041
You can already use it by installing ESLint from that pull request commit:
npm install 'git+https://github.com/doberkofler/eslint.git#2c90b91e97389453a92affee3496d26cf69b9fe8'
and/or:
sudo npm install -g 'git+https://github.com/doberkofler/eslint.git#2c90b91e97389453a92affee3496d26cf69b9fe8'