Merges master into branch 1061592. adds checkbox, stores pref on server and local

@Rik r? This is the first part of a two steps. I had to split this into two, to clean up the other pull request that was merged and then backed out and, to create smaller easier/faster to review pull requests.

This pull requests:

1) Adds the checkbox to enable or disable new comment notifications
2) Send and stored that value on the server in user.settings
3) Updates the local user data with the same preference also stored in the user.settings array
Instead of a "global" variable, I think we can just wrap the nunjucks render with a get_user() call since it's the only time we use it.