Update MMk, MyModelArgs demos => require_relative

demos/MMk.rb

 #!/usr/bin/env ruby
 
 require 'rubygems' if RUBY_VERSION =~ /^1\.8/
-require 'simplekit'
+require_relative '../lib/simplekit'
 
 # Demonstration model of an M/M/k queueing system.  There are k servers
 # and both the arrival and service processes are memoryless (exponential).

demos/MyModelArgs.rb

 #!/usr/bin/env ruby
 
 require 'rubygems' if RUBY_VERSION =~ /^1\.8/
-require 'simplekit'
+require_relative '../lib/simplekit'
 
 class MyModel
   include SimpleKit