fixed require_path, removed demos

Signed-off-by: pjs <pjs@alum.mit.edu>

simplekit.gemspec

@@ -10,17 +10,13 @@ Gem::Specification.new do |s|
   s.email = "pjs@alum.mit.edu"
   s.description = "This is a minimal discrete event simulation scheduling algorithm for educational use."
   s.author = "Paul J Sanchez"
-  s.require_path = %[.]
   s.files = %w[
     simplekit.gemspec
     ReadMe.1st
-    demos/MMk.rb
-    demos/MyModel.rb
-    demos/MyModelArgs.rb
-    depend extconf.rb
     lgpl.txt
     lib/simplekit.rb
   ]
   s.add_runtime_dependency 'pqueue', '~> 2.0.2'
+  s.required_ruby_version = '>= 1.8.1'
   s.license = 'LGPL'
 end