Adding tcli_connection options database

[yuua]

Thank you for this great library!

I wasn't able to specify the database name other than the default

I changed it in order to add database to option in tcli connection.

sample

RBHive.tcli_connect(hive.address,hive.port,{database: 'hogehuga'}) do |c|
  c.fetch 'show tables'
end

For this reason, I have sent a pull request.

Thank you.