adding JDBC support

* This is mostly cribbed from the old Sequel-Rails3 gem (https://github.com/gucki/sequel_rails3/blob/master/lib/sequel_rails3/configuration.rb)
* Allows native JRuby connections
allowing JDBC access to `Storage` as well
using actual config components for jdbc

The presence of querystrings meant parsing db name, etc., was _really_
tricky and often wrong. Making this explicit fixes that.
Merge pull request #21 from JackDanger/jackdanger/jdbc-connections

Fixing JDBC support
Update history with changes from Jack Danger Canty
Fix warning about secret token
Run spec with JDBC adapters on JRuby and add JRuby to TravisCI