Removed Hash[] idiom for creating row Hash for Reader#each
Removed Hash[] idiom for creating row Hash for Reader#each

* rsim brought up the valid point that in the future Reader#values may
  be an Array (at least could be with do_oracle), and using
  Enumerable#flatten on the values could break things.

  Changed the code to use the simplest approach I could think of, that
  will not have the same issues.

simonkro/do_mysql,simonkro/do_mysql,simonkro/do_mysql