Fixed "two few options" errors.
Allow the second argument of download() to be a directory.
Copy arguments to named local vars for readability.
Added support for *.tgz, *.tbz, *.tbz2 to extract().
Moved the cd into bin/ruby-install and use `patch -d`.
Added the stdout-rouge-fix.patch for Ruby 1.8.x.
Install rubygems for ruby 1.8.x.
Also apply the stdout-rouge-fix.patch for 1.8.x.