Removed sample31 from the list of working samples for now

* not working on Linux and Mac
* please reference #276
* [skip ci]
Cleaned up the bin directory of swt-shoooes stuff

* now there are only 3 executables: shoes, shoes.bat and ruby-shoes
* done to avoid confusion as to which executable to use
* Adjusted the Rakefile to reflect... as for my understanding the
  check for the Host OS could be removed and I did it... don't
  have shoes on Windows set up yet - @ashbb may you please check
  if running the samples still works?
* adjusted README
* [skip ci]