Support single redis DB.
Various cleanups to Ubuntu installation instructions:

* Avoid editing /etc/apt/sources.list add nginx repo, instead create
  /etc/apt/sources.list.d/nginx.list

* Avoid editing /etc/nginx/nginx.conf, instead put server_name_hash_buckets
  setting into discourse.conf

* Proper-case Discourse when it is referring to the product name, so that all
  the lowercase references are to the user created during the installation
Address @Supermathie's concerns in PR1430
Locate the Puma config file.
Update puma.rb
Russian translation (actual version)
fix spec, categories without position are now always at the end of the list
Admin Quick Start Guide: Change email test link

The feature has moved from `/admin/email/logs` to `/admin/email`.
[0] is shorter than [0,1] :)
FIX: ensureMaximumDimensionForImagesInPreview wasn't always working
only display inline HTML revision history on mobile
move arbitrary html content out of noscript and into the preloadstore
create_account_controller.js passwordRequired needs the same logic as user_authenticator. Make twitter and facebook signup work again.
FIX: deprecation warning in create_account_controller.js. Need to move createAccount into actions.
FIX: category_list_spec should not expect deterministic order
use a helper instead of a view for custom HTML content
Merge pull request #1742 from joallard/patch-1

[minor] Admin Quick Start Guide: Change email test link
Improve how category stats are rendered
Improve tooltip on categories stats.
FIX: Title text should be correctly escaped since we are generating a raw html.