fix gemspec dependency

taiwan_city.gemspec

@@ -24,7 +24,6 @@ Gem::Specification.new do |s|
   s.add_development_dependency "sqlite3"
   s.add_development_dependency "rspec-rails"
   s.add_development_dependency "coffee-rails"
-  s.add_development_dependency "jquery-rails"
   s.add_development_dependency 'capybara'
   s.add_development_dependency 'launchy'
   s.add_development_dependency 'poltergeist'