Various fixes (ruby 1.9 and bundler) and internals

Fixed support for Ruby 1.9, gemspec. Extracted VERSION to a separate file, and changed file extensions for additional files (*.rdoc). For use with JRuby 1.7.3, and bundler 3.0.4.

Internally I've fixed: Import nested modules/ packages, Conversion reference Py_IncRef,
interpreter real name target instead of library (as https://github.com/steeve/rupy does); Added tests for optional named args functions (rspec and python function).

PS. I require some python native packages in my rails environment, to completed the bridge for my needs I've fixed/ added the above (some other fixes might follow).