Don't show empty brackets in log files

The current log files generated by Laravel all show empty brackets at the end of log files. We can remove these by using the $ignoreEmptyContextAndExtra parameter in the default Monolog LineFormatter.

@seldaek I was wondering why this isn't set to true by default?

http://stackoverflow.com/questions/13968967/how-not-to-show-last-bracket-in-a-monolog-log-line