remove coffee-script-source from dependency

Author: chulkilee

react-rails.gemspec

@@ -28,7 +28,6 @@ Gem::Specification.new do |s|
   s.add_development_dependency 'turbolinks', '>= 2.0.0'
   s.add_development_dependency 'rails', '>= 3.2'
 
-  s.add_dependency 'coffee-script-source', '~>1.8'
   s.add_dependency 'connection_pool'
   s.add_dependency 'execjs'
   s.add_dependency 'railties', '>= 3.2'