UAS: Now received STATUSTEXT messages are output to stdout.

UAS.cc, where all messages are handled, now outputs any received STATUSTEXT message to stdout with the UAS ID, severity, and message. This is used instead of qDebug(), because that always outputs to stderr. This text is output that would be valuable in a release build, so it should be output to stdout.

This makes it easier for the operator to see the history of text messages in case they miss a couple.

I believe a follow-up should also make all messages that are of a CRITICAL severity or higher get said using the Speech API even if they don't start with "#audio:".