a bit more new user welcome tweaks
remove unnecessary pre/code base CSS
FIX: reworked handling URL bbcode tags
Remove deprecated `Ember.Deferred`
Suppress images for short emails
Merge pull request #2805 from techAPJ/patch-1

Suppress images for short emails
Renaming site contents to site text
Update i18n keys for site_content rename
FIX: automatic backup uploads to S3 when using a region
Update DEVELOPER-ADVANCED.md

ruby 2.1.3 not 1.9 ... no longer supported
Merge pull request #2820 from Elberet/fix-url-bbcode

FIX: reworked handling URL bbcode tags
remove cruft
SECURITY: rate limit user/password login
update sidekiq to latest
UX: fix typo in lazyYT.css
Update gems
FEATURE: airbrake dependency removed, can be added via a plugin if needed
update gems
gem updates
Gem updates, all up to latest.