sqm-scripts: Fix a minor bug, add copyrights, improve logging

Changes committed to the cerowrt original repo after the initial import here:
 - Better license & copyright statements, as requested
 - Fixed a minor bug in stopping sqm
 - Logging improvements
 - Dead code removed
 - Typos corrected

Signed-off-by: Hannu Nyman <hannu.nyman@iki.fi>
Merge pull request #442 from hnyman/patch-sqm

sqm-scripts: Fix a minor bug, add copyrights, improve logging