ruby: v↑ ruby2.1 (2.1.8)

Ruby 2.1.8 contains security and other bugfixes

    https://www.ruby-lang.org/en/news/2015/12/16/ruby-2-1-8-released/

component/ruby/buildout.cfg

@@ -26,8 +26,8 @@ environment =
 
 [ruby2.1]
 <= ruby-common
-url = http://ftp.ruby-lang.org/pub/ruby/2.1/ruby-2.1.7.tar.xz
-md5sum = 2e43a1d32cc16975a6b5d3ffce399199
+url = http://ftp.ruby-lang.org/pub/ruby/2.1/ruby-2.1.8.tar.xz
+md5sum = f18ed96bd1d5890f97a17d0d17aaefdd
 
 
 [ruby2.2]