ruby: Follow to rubyX.y parts naming

Like with e.g. python or readline, or like with versioned programs e.g.
on Debian, put version into name without dash. So

    ruby-2.2 -> ruby2.2

/cc @kazuhiko

component/ruby/buildout.cfg

@@ -12,7 +12,7 @@ extends =
 
 parts = ruby
 
-[ruby-2.2]
+[ruby2.2]
 recipe = slapos.recipe.cmmi
 url = http://ftp.ruby-lang.org/pub/ruby/2.2/ruby-2.2.2.tar.xz
 md5sum = dbce9b9d79d90f213ba8d448b0b6ed86
@@ -26,4 +26,4 @@ environment =
   PKG_CONFIG_PATH=${libyaml:location}/lib/
 
 [ruby]
-<= ruby-2.2
+<= ruby2.2