#34: added Hook model, controller, views
#34: update controller, views, model of Hook
#34: update UI
#34: update messages, comments
#34: added before_validation for Hook model
#34: update ability.rb
#34: added specs for Hooks controller
#34: added new hooks, some refactoring according to Alexander's comments
#34: revert schema.rb
#34: update db/schema.rb
#34: update hook.en.yml and hook.ru.yml
#34: added names of new hooks
#34: added support of hooks for issues.
#34: fixed double notification
#34: added #receive_push action
#34: update application.yml.sample
#34: temporarily disabled hipchat
#34: merge master into branch
#34: updated Hook model
#34: updated #show