Added: Cassandra Storage

This update adds Cassandra as a possible storage driver:

• CASSANDRA_CONTACT_POINTS: Set the cassandra host(s)
• CASSANDRA_USERNAME: Set the cassandra username
• CASSANDRA_PASSWORD: Set the cassandra password
• CASSANDRA_KEYSPACE: Set the keyspace you've created the tables in
• CASSANDRA_PORT: Defaults to 9042 - set the port of the cassandra host(s)

There are no migrations, so you'll need to manually add the keyspace/tables - there is an example of a setup script in the storage folder.

Full Changelog: v0.3.3...v0.4.0