Ruby 1.9.3 Support

Reference: https://github.com/banister/texplay/issues/26

Ruby 1.9.3 does not support `rb_obj_reveal` so ifdef conditionals were added to allow the gem to be compiled.
FIX: Ruby Version Checking in Extension

If the major version is 1 (shorthand for checking for Ruby 1.9.3) or if the major is 2 and minor is 0 (2.0) then we want to do things the old-fashioned way.
Merge pull request #28 from burtlo/support/ruby-193

Ruby 1.9.3 Support