Don't require json_pure

jasmine.gemspec

@@ -52,10 +52,10 @@ Gem::Specification.new do |s|
   s.add_development_dependency 'rack-test'
   s.add_development_dependency 'gem-release', ">= 0.0.16"
   s.add_development_dependency 'ci_reporter'
+  s.add_development_dependency 'json_pure'
 
   s.add_dependency 'jasmine-core', ">= 1.1.0.rc2"
   s.add_dependency 'rack', '>= 1.1'
   s.add_dependency 'rspec', '>= 1.3.1'
-  s.add_dependency 'json_pure', '>= 1.4.3'
   s.add_dependency 'selenium-webdriver', '>= 0.1.3'
 end

lib/jasmine/tasks/jasmine.rake

@@ -3,8 +3,17 @@ namespace :jasmine do
     require 'jasmine'
   end
 
+  task :require_json do
+    begin
+      require 'json'
+    rescue LoadError
+      puts "You must have a JSON library installed to run jasmine:ci. Try \"gem install json\""
+      exit
+    end
+  end
+
   desc "Run continuous integration tests"
-  task :ci => "jasmine:require" do
+  task :ci => ["jasmine:require_json", "jasmine:require"] do
     if Jasmine::rspec2?
       require "rspec"
       require "rspec/core/rake_task"