traceback when syslog server in fotoobo.yaml is not resolvable

[patrikspiess]

If you set a syslog server in fotoobo.yaml for logging which is not resolvable by dns (name not known or timeout) it gives a treaceback:

socket.gaierror: [Errno -2] Name or service not known

or

socket.gaierror: [Errno -3] Temporary failure in name resolution

Instead fotoob should give a propper error message (and maybe continue anyway?)