* common.mk: use ruby organization for rubyspec.

	* spec/default.mspec: remove specific version number.
	  https://github.com/ruby/rubyspec/commit/7a909e925c1baa9c700bd44af9241aef6e596714

	* spec/default.mspec: use default configuration file name.
	  https://github.com/ruby/rubyspec/commit/cc69f337b06362e5607ffa3e3ad40ef7494960cf


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@50069 b2dd03c8-39d4-4d8f-98ff-823fe69b080e