Add ruby-1.9.3-p392

http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-list/49192 (release mail in Japanese)
http://svn.ruby-lang.org/repos/ruby/tags/v1_9_3_392/ChangeLog

Requesting a pull to wayneeseguin/rvm from hokkai7go/193p392
http://www.ruby-lang.org/en/news/2013/02/22/ruby-1-9-3-p392-is-released/