Write auxiliary info to the system's error stream and not to the std output.

When executing a Cassandra script from the terminal then all output is written to the standard output stream of the system. For example if we create a file called my_script with the following commands:

use MyKeyspace;
show schema;

and we execute it as:

cassandra-cli < my_script > my.scm

then the output file my.scm will also contain lines like:

Connected to: "Test Cluster" on 127.0.0.1/9160
Welcome to Cassandra CLI version 1.2.0-SNAPSHOT

Type 'help;' or '?' for help.
Type 'quit;' or 'exit;' to quit.

or

Authenticated to keyspace: MyKeyspace

Would be good to write such information to the system error stream so that one would be able to do:

cassandra-cli < my_script > my.scm 2> /dev/null