storage: support specifying normalizer in table comment

I've modified based on your comments https://github.com/mroonga/mroonga/pull/26 .

> Please recreate database for stable dump output. See also 3acf106

This test didn't use the ``dump`` command.
It uses ``SELECT`` SQL in the same way as the following test case.

https://github.com/mroonga/mroonga/blob/master/mysql-test/mroonga/storage/create/table/normalizer/t/fulltext_index.test