rdoc should not be required

Rakefile

@@ -1,21 +1,28 @@
 require 'bundler'
-require 'rdoc/task'
+
 Bundler::GemHelper.install_tasks
 
 $LOAD_PATH.unshift 'lib'
 
 task :default => :test
 
+# Tests
 desc "Run tests"
 task :test do
   Dir['test/*_test.rb'].each do |f|
     require File.expand_path(f)
   end
 end
 
-Rake::RDocTask.new do |rd|
-  rd.main = "README.markdown"
-  rd.rdoc_files.include("README.markdown", "lib/**/*.rb")
-  rd.rdoc_dir = 'doc'
+# Documentation Tasks
+begin
+  require 'rdoc/task'
+
+  Rake::RDocTask.new do |rd|
+    rd.main = "README.markdown"
+    rd.rdoc_files.include("README.markdown", "lib/**/*.rb")
+    rd.rdoc_dir = 'doc'
+  end
+rescue LoadError
 end