Cleanup rakefile

Rakefile

@@ -1,19 +1,20 @@
-require 'rubygems' unless defined?(Gem)
-require 'rake'     unless defined?(Rake)
-import  *Dir['tasks/*.rake']
+require 'rubygems'
+GEMSPEC = Gem::Specification.load('eventmachine.gemspec')
 
-GEMSPEC = eval(File.read(File.expand_path('../eventmachine.gemspec', __FILE__)))
-
-require 'yard'
 require 'rake/clean'
 task :clobber => :clean
 
 desc "Build eventmachine, then run tests."
 task :default => [:compile, :test]
 
 desc 'Generate documentation'
-YARD::Rake::YardocTask.new do |t|
-  t.files   = ['lib/**/*.rb', '-', 'docs/*.md']
-  t.options = ['--main', 'README.md', '--no-private']
-  t.options = ['--exclude', 'lib/jeventmachine', '--exclude', 'lib/pr_eventmachine']
+begin
+  require 'yard'
+  YARD::Rake::YardocTask.new do |t|
+    t.files   = ['lib/**/*.rb', '-', 'docs/*.md']
+    t.options = ['--main', 'README.md', '--no-private']
+    t.options = ['--exclude', 'lib/jeventmachine', '--exclude', 'lib/pr_eventmachine']
+  end
+rescue LoadError
+  task :yard do puts "Please install yard first!"; end
 end