FORCE_GC=false causes NPE in log

If IlluminaBasecallsToFastq is started with FORCE_GC=false a NullPointerException is written to the log. Fixed by adding a check before calling gcTimerTask.cancel()

Also change the System.out.println() calls to log.info(). Better to have all information go through the logging mechanism so that the output can be controlled with the VERBOSITY parameter.

/Nicklas