By default, if a path does not match any formatter a log message at WARN level will be emitted. A user can change this by providing the `--on-unmatched` or `-u` flag and specifying a log level `debug,info,warn,error,fatal`.
If fatal, the process will exit with an error on the first unmatched path encountered.
Closes#302
Signed-off-by: Brian McGee <brian@bmcgee.ie>
