OTWO-1206 Updates SWIG bindings to Ruby 1.9.2

OTWO-1206 Updates SWIG bindings to Ruby 1.9.2

- Requires SWIG 2.0.4 (SWIG 1.3 is not compatible with Ruby 1.9.2)

This updates the SWIG bindings only. This code tree does not build:

- Build fails for me when using RVM Ruby 1.9.2 because 'ruby.h' and
  'config.h' headers cannot be found. I am currenty working around
  this by manually placing absolute paths in the build script.

- test/unit/ruby/source_file_test.rb is currently failing because the
  round trip from Ruby -> C -> Ruby causes the string encoding
  metadata to be lost. UTF-8 input strings are output with identical
  content bits, but are marked as ASCII-8BIT.