Deleted a debug output. Refs #7789.
Modified some logging. Refs #7789.
Refs #7789.  Fixed an error about best result.

And also modified for better logging.
Refs #7789.  Enhanced for low signal noise ratio peak.

1. Add option to use given peak position other than use observed peak
centre.
2. If FindPeaksBackground fails, then use some heuristic algorithm to
give a peak range for fitting background.