maxpasswd writes notice message to stdout

The maxpasswd utility writes a notice message to stdout, which means it's very difficult to capture the output of the maxpasswd tool, which is required in order to obtain the password in a script.

This broke my automated MaxScale deployments.

# maxpasswd /var/lib/maxscale/data/ mypassword 2>/dev/null

6E37E9B0CA3BF6020A3DBCD0DE113546

2016-03-31 17:17:37   notice : Using encrypted passwords. Encryption key: '/var/lib/maxscale/data/.secrets'.