- RFC3164 references the "notice" log level.  Even though Catamaran doesn't currently support notice, leave room in the numbering.
- Use the term 'severity' in place of 'log_level' when referring to individual log messages.
- There is some debate as to whether or not INFO logging should be enabled by default.  RFC3164 recommends the existence of NOTICE log level in between INFO and WARN.   Introducing it and setting it as the default is beneficial in two ways.  (1) It creates a production-ready logging severity that is informative in nature (2) It creates a log level that is more critical than DEBUG that is NOT captured by default.   Not all low-severity log messages have equal weight and it's valuable to have a few levels to work with (TRACE, DEBUG, and INFO)
- Small performance boost to LogLevel.severity_to_s