changed the order in which the required files are loaded

Had this problem while trying to follow along with the README for this project. 
$ irb
irb(main):001:0> require 'koi-vm-ruby'
NameError: uninitialized constant KoiVMRuby::VM::EQUAL
        from /usr/lib/ruby/gems/1.9.1/gems/koi-vm-ruby-0.0.4/lib/koi-vm-ruby/opcodes/comparative_operations/equal.rb:4:in `<class:VM>'
        from /usr/lib/ruby/gems/1.9.1/gems/koi-vm-ruby-0.0.4/lib/koi-vm-ruby/opcodes/comparative_operations/equal.rb:2:in `<module:KoiVMRuby>'
        from /usr/lib/ruby/gems/1.9.1/gems/koi-vm-ruby-0.0.4/lib/koi-vm-ruby/opcodes/comparative_operations/equal.rb:1:in `<top (required)>'
        from /usr/lib/ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
        from /usr/lib/ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
        from /usr/lib/ruby/gems/1.9.1/gems/koi-vm-ruby-0.0.4/lib/koi-vm-ruby.rb:9:in `block in <top (required)>'
        from /usr/lib/ruby/gems/1.9.1/gems/koi-vm-ruby-0.0.4/lib/koi-vm-ruby.rb:8:in `each'
        from /usr/lib/ruby/gems/1.9.1/gems/koi-vm-ruby-0.0.4/lib/koi-vm-ruby.rb:8:in `<top (required)>'
        from /usr/lib/ruby/1.9.1/rubygems/custom_require.rb:60:in `require'
        from /usr/lib/ruby/1.9.1/rubygems/custom_require.rb:60:in `rescue in require'
        from /usr/lib/ruby/1.9.1/rubygems/custom_require.rb:35:in `require'
        from (irb):1
        from /usr/bin/irb:12:in `<main>'


So this commit fixes that issue.

$ irb
irb(main):001:0> require './lib/koi-vm-ruby'
=> true
irb(main):002:0>