Refactor: Topic#invite_by_email

Extract Topic#email_already_existas_for? and Topic#grant_permission_to_user
Fix failing spec due to missing variable in extracted method
Add script to install mandatory config files from their .sample version.
Standardize on 'worker' for sidekiq Procfile entry (expected by buildpack).
Copy default production.rb file.
Allow to set SMTP settings via environment variable.
better file upload dialog
more vertical space in the upload selector dialog
FIX: category validation in composer was still using categoryName instead of categoryId
When creating a topic, don't select a category by default when allow_uncategorized_topics is false. Also, added category validation on the server to enforce allow_uncategorized_topics.
Only show filter button if the user has more than 2 posts
add current_user_provider so people can override current_user bevior cleanly, see

http://meta.discourse.org/t/amending-current-user-logic-in-discourse/10278
require dependency was leading to errors in dev
Improve login modal on mobile
Russian translation (actual version)

 * Migrating from crowdin to transifex translation service (free & less bugs)
 * Reformats YML as transifex service do
Pressing enter in username field of login form will submit the form
Allow Youtube onebox with start time. All params are used in the youtube onebox now.
refactors Discourse.Model to bind context to self plus some minor clean-ups
removes unused context binding from Discourse.Site
Russian translation (actual version)

Fix YML numeric keys