* lib/rss/maker/{1.0,0.9,2.0}.rb: changed RSS Maker to raise
RSS::NotSetError if required values of maker.channel are not
set.
* test/rss/test_maker_{1.0,0.9,2.0}.rb: changed tests to check RSS
Maker raises or not.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@7401 b2dd03c8-39d4-4d8f-98ff-823fe69b080e