Adding Regular Expression koans.

koans/path_to_enlightenment.rb

@@ -8,6 +8,7 @@ require 'about_arrays'
 require 'about_array_assignment'
 require 'about_hashes'
 require 'about_strings'
+require 'about_regular_expressions'
 require 'about_methods'
 require 'about_constants'
 require 'about_control_statements'