Minor changes to Report, Query, and Hit classes.

* Report#parameters is now Report#params and returns a Hash.
* Query#meta is now Query#title.
* Hit#def is now Hit#title.

The last two changes aims for consistency with Sequence class, which derives
terminology from blastdbcmd's outfmt option.

Signed-off-by: Anurag Priyam <anurag08priyam@gmail.com>