GUACAMOLE-269: Don't abort on ttymode issue, just log a warning.
GUACAMOLE-269: Don't abort on ttymode issue, just log a warning.

apache/guacamole-server,mike-jumper/incubator-guacamole-server,glyptodon/guacamole-server,glyptodon/guacamole-server,mike-jumper/incubator-guacamole-server,glyptodon/guacamole-server,apache/guacamole-server,apache/guacamole-server,mike-jumper/incubator-guacamole-server,mike-jumper/incubator-guacamole-server