Release Name: 1.1.8

Notes:
* Bug fix for File.nl_convert
* Cleanup


Changes:
* Fixed some bad variable names that crept into the File.nl_convert method.
* Added the File.null_device alias for File.null.
* Added cygwin and mingw to Windows detection code.
* One of the nlconvert tests is now skipped on Windows.
* Two text files that were previously bundled as part of this library for
  testing purposes have been removed. Those are now dynamically generated
  within the tests themselves.
* Gemspec updates.
* Documentation updates.
* Added the :gem rake task.