assertions.rb: assert_all? assert_not_all?

* lib/test/unit/assertions.rb (assert_all?, assert_not_all?): new
  assertions for all iterations.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45222 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* test/csv/test_data_converters.rb: use descriptive assertions.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45223 b2dd03c8-39d4-4d8f-98ff-823fe69b080e