Add impressionist

Gemfile

@@ -31,6 +31,8 @@ gem 'sprockets'
 gem 'tinymce-rails'
 gem 'therubyracer' if RUBY_PLATFORM.downcase.include?("linux")
 
+gem "impressionist", :require => "impressionist", :path => "vendor/impressionist"
+
 # Gems used only for assets and not required
 # in production environments by default.
 group :assets do