JNA support and minor bugfixes

* Added recipe cassandra::jna in order to download and enable JNA for cassandra (http://www.datastax.com/documentation/cassandra/1.2/webhelp/cassandra/install/installJnaDeb.html).
* Fixed minor bug on service "cassandra" statement that was preventing cassandra from starting successfully in the first run.
* Added package management dependencies again (was removed by mistake on last pull request)