Add notification for expired steam token

[viper2097]

Wanted to play with my friends again yesterday, unfortuantely it was not possible to open a server as it just closed and shut down seconds after launching it.
Was not able to sort it out yesterday, so I took a look into the logs today.

After finding the correct log, the problem was quite clear:

Maybe it would be a good idea, that csgosl could recognize that message somehow and point it out to the user. I was now able to sort it out, but yesterday, I had no clue. Right now, the window just closes immediately and you don't have any kind of a chance to read, or even see that message.

[lenosisnickerboa]

Yup, I'll add this as a possible future enhancement. Good idea!

Output from server when update is needed:

Your server needs to be restarted in order to receive the latest update.
MasterRequestRestart
Your server needs to be restarted in order to receive the latest update.
MasterRequestRestart
Your server needs to be restarted in order to receive the latest update.
MasterRequestRestart