Add Handlebars
Merge branch 'feature/widget-direction' into feature/widget-direction-printing

* feature/widget-direction: (37 commits)
  Use proper import paths in direction widget’s print stylesheet
  Import mixins in every stylesheet
  Update autoprefixer-rails
  fix: Forward `params` hash instead of hard coded value
  fix: Include full descendants objects in the relic:export task
  Don’t include Antiscroll if it’s not used
  readme: Freeze elasticsearch and postgresql versions
  Don’t trim the string
  Tweak the styles of the empty frame
  Remove some orphaned vendor-prefixed properties
  Rewrite the structure of Redactor’s stylesheet
  Slightly delay the execution of loaded widget’s callback
  Slightly tweak the view of the embedded widget in the sidebar
  Make the Add Alert widget a little responsive
  Make the sidebar widget code easily selectable
  Sidebar widget: make the animation less chaotic on load
  Use translation strings for the sidebar widget
  Give the sidebar widget a look
  Raw implementation of the sidebar widget
  Allow for anonymous widget alert
  ...

Conflicts:
	Gemfile
Use Handlebars when appending relics to the print page
Style the widget direction printing page
Prevent from adding duplicated relics to the printed list
Notify when loading the relic list to print
Display fallback address
Display relic’s place if available
Include the credits on the printed page
Merge branch 'feature/widget-direction-printing' into feature/widget-direction

* feature/widget-direction-printing:
  Include the credits on the printed page
  Display relic’s place if available
  Display fallback address
  Notify when loading the relic list to print
  Prevent from adding duplicated relics to the printed list
  Style the widget direction printing page
  Use Handlebars when appending relics to the print page
  Add Handlebars