update

Gemfile

@@ -1,7 +1,11 @@
 source 'https://rubygems.org'
 
 # as web framework
-gem 'rails', '~> 4.1'
+gem 'rails', '~> 4.2'
+
+# respond_to methods have been extracted to the responders gem
+# http://edgeguides.rubyonrails.org/upgrading_ruby_on_rails.html#responders
+gem 'responders', '~> 2.0'
 
 # as the database for Active Record
 gem 'mysql2'
@@ -49,20 +53,44 @@ gem 'bootstrap-sass', '~> 3.3.4.1'
 gem 'autoprefixer-rails'
 gem 'formtastic-bootstrap'
 gem 'formtastic', '~> 2.3.0.rc3'
-gem 'momentjs-rails', '>= 2.8.1'
-gem 'bootstrap3-datetimepicker-rails', '~> 3.0.2'
+gem 'cocoon'
+
+# frontend javascripts
 
 # as the JavaScript library
 gem 'jquery-rails'
-gem 'cocoon'
+
+source 'https://rails-assets.org' do
+  # for placeholder images
+  gem 'rails-assets-holderjs'
+  # for formating dates
+  gem 'rails-assets-date.format'
+  # for or parsing, validating, manipulating, and formatting dates.
+  gem 'rails-assets-momentjs'
+  # for smooth scrolling
+  gem 'rails-assets-jquery-smooth-scroll'
+  # as color picker
+  gem 'rails-assets-spectrum'
+  # for color manipulation
+  gem 'rails-assets-tinycolor'
+  # for drawing triangle backgrounds
+  gem 'rails-assets-trianglify'
+  # for scroll way points
+  gem 'rails-assets-waypoints'
+  # for displaying maps
+  gem 'rails-assets-leaflet'
+end
+
+# as date picker
+gem 'bootstrap3-datetimepicker-rails', '~> 3.0.2'
 gem 'jquery-datatables-rails', '~> 2.2.1'
+# for charts
+gem 'd3_rails'
+gem 'chart-js-rails'
 
 # for user avatars
 gem 'gravtastic'
 
-# for maps
-gem 'leaflet-rails', '~> 0.7.4'
-
 # for country selects
 gem 'country_select', github: 'stefanpenner/country_select'
 
@@ -75,10 +103,6 @@ gem 'prawn_rails'
 # to render XLS spreadsheets
 gem 'axlsx_rails'
 
-# for charts
-gem 'd3_rails'
-gem 'chart-js-rails'
-
 # as error catcher
 gem 'hoptoad_notifier', '~> 2.3'
 
@@ -121,6 +145,7 @@ gem 'acts_as_list'
 # for switch checkboxes
 gem 'bootstrap-switch-rails', '~> 3.0.0'
 
+# for parsing OEmbed data
 gem 'ruby-oembed'
 
 # Use guard and spring for testing in development
@@ -138,6 +163,7 @@ group :development do
   gem 'letter_opener'
   # mina is a blazing fast deployment system
   gem 'mina'
+  gem 'web-console', '~> 2.0'
 end
 
 # Use rspec and capybara as testing framework