VM can handle assignment to a global variable

One line closer to be able to execute the helper script for rubyspecs.

Currently need the following to complete the ruby_executable_hooks helper:
  * Process class
  * Process#setproctitle
  * Array#include?
  * require 'rubygems'
  * begin ; rescue; end
  * Gem class
  * defineable classes with methods
  * Kernel#warn
  * Env class
  * Hash#key?
  * eval
  * File.read
  * binding
Tidy up build script a bit
Add script to run rubyspec
Handle inline if and unless

Was surprised I hadn't caught UNLESS in the last round of keyword support.
This is mostly to get one step further in the rubyspec executable helper
script.
Add a stub of the Process class
Implement stub of TrueClass and FalseClass
implement Array#include?
Implement If / Else blocks
Single quote strings are parsed without '

I'm not sure why this ever seemed like a *good* idea to me. Upon reflection,
it's really awful. Using the type system to discover which type of
string you actually are dealing with is a much more powerful technique and
it doesn't require you to slide off the quotes anytime you want the string
literal (e.g.: when you're treating it as a filename for Kernel#require).

Incidentally, this also adds the behavior of ignoring 'rubygems' for
Kernel#require.