Option to disable avahi

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The problem
I run snapserver in a docker and I don't need/want it to announce itself on the network. It keeps trowing an error because avahi isn't running although snapserver works perfectly fine without it. It is not a huge deal but getting error-messages when everything works as expected is kinda odd and sometimes confusing for some users.

Suggested solution
Either turn this message into a warning or better, make the use of avahi optional through config-file and/or command-line-parameter.