add knowledge of pacman and arch dependencies
don't extract verbose
Strip whitespace before checking if String is empty.
We now support Arch Linux thanks to @charliesome!
Strip both leading and tailing whitespace.
Include 2.0.0-p0.
Use extended globbing to strip whitespace.
Extract the first two digits from RUBY_VERSION for RUBY_URL.
80 columns.
Style.
Run package manager commands under sudo.

* brew will automatically run sudo under the hood.
Added missing comments.
Added verify_ruby which checks the MD5 checksum of the archive.
Added error messages to verify_ruby().
Imported MD5 checksums from RVM.

* Source: https://github.com/wayneeseguin/rvm/blob/master/config/md5
Manually add checksums for rubinius 1.2.4 and 2.0.0-rc1.
Use md5.txt.
sudo all apt-get / yum commands.
Better log message.
Renamed warning to warn.