Implement standard truststore & keystore handling as follows:

• Support provision of cassandra_keystore_path, cassandra_keystore_password, cassandra_truststore_path, cassandra_truststore_password through the cassandra section of the AUTO.json file
• In BE_2_setup_configuration.rb, set the values of cassandra_keystore_path, cassandra_keystore_password, cassandra_truststore_path, cassandra_truststore_password in janusgraph.properties based on the values from AUTO.json