related to FTS ranking. We use "term frequency–inverse document frequency"
type of ranking calculation. So ranking might be exactly the same as the
one used MyISAM, however, the general ranking Order should be the same.

Also removed "default_engine" reference in the tests, and use "engine = InnoDB"
explicitly so we can just run the test suite by "--suite=innodb_fts"
without specifying ignoring or using a particular storage engine.

Some queries are quoted out because we do not support such. Any changed
queries are commented with "INNODB_FTS" key word, mostly are related to

1) Command not support by InnoDB, such as "repair", "optimize" and "ignore key"
2) Charset support (need enhance)
3) InnoDB do not support FT type queries on table without FTS index
4) Check table not yet supported on FTS
5) Misc item, such as "apostrophe" support etc.