[NewFeature] use acts_as_commentable_with_threading gem
[NewFeature] import keywords information
[NewFeature] add question scaffold
[NewFeature] add admin/question controller and views
[NewFeature] add link model and table
[NewFeature] edit question, add comments
[NewFeature] use sidekiq gem
[NewFeature] list question in front page
[Improve] change question migration
[NewFeature] keywords management
[Improve] add status to keywords and questions table
[Improve] fix keyword controller bug
[Improve] change newrelic config and version