Double quote in user agent causes malfomed log file
Some devices include a double quote character in their user agent.
The icecast log file quotes the user agent field, but does not escape any quotes inside of this, causing an invalid format. Example:
"Mozilla/5.0 (Linux; Android 5.1; Alba 8" Build/LMY47I) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/55.0.2883.91 Safari/537.36"