Added `openssl_verify_mode` parameter for action_mailer.

- parameter in `environments/production.rb`
- documentation & default value (nil) in `discourse_defaults.conf`
Update discovery_topics_view.js

I guess this is a typo
fix funky French language on 503 error page.
BUGFIX: initial migrate was broken cause bust schema was cached
Merge pull request #2337 from awesomerobot/master

lighter TH on topic-list
FEATURE: logster env tab, log current user
BUGFIX: 500 error on missing category
BUGFIX: failing avatar detection job
FEATURE: add the first 3 participants in a private message
FEATURE: remove bookmark button in activity feed
BUILD FIX: missed a semicolon
BUGFIX: remove N+1 on topic lists
BUGFIX: 404 on /users/:user/private-messages
BUGFIX: do not lightbox oneboxed images
Merge pull request #2332 from rhacker/patch-1

Update discovery_topics_view.js
Merge pull request #2334 from pierremanceaux/master

fix funky French language on 503 error page.
BUGFIX: could not see the revisions of a post in a deleted topic
In web crawler mode, don't show a previous link on a page with 0 results. Google will index those pages and keep following the prev links.
TRIVIAL: slightly better information when logging download error
ES6: Notification controllers, added helper to create via ES6/container