Added detailed error message. Refs #7789.
Modified 2 log output to information. Refs #7789.

The reason to change them from warning to information is that
GetDetOffsetsMultiPeak() will call Fit() millions of time in a typical
calibration.  There is no way to hide warning log in MantidPlot.
Made a series minor changes including ... .  Refs #7789.

1. Corrected discrpencies in cost function name;
2. Refactored logging in class FitOneSinglePeak;
3. Added debug output
Added one more column in output table workspace. Refs #7789.
Replaced code to fit peak by FitOneSinglePeak. Refs #7789.
Fixed an error caused by change in FindPeaksBackground. Refs #7789.
Modified to fix unit test failure of StripPeaks. Refs #7789.
Cleaned the code in unit test. Refs #7789.
Modifed due to change in output of FindPeaks. Refs #7789.
Changed unit test for better performance. Refs #7789.
Added more detailed error message to track bug. Refs #7789.
Added a check to find out occasional OSX error. Refs #7789.
Fixed a bug. Refs #7789.
Removed the doxygen warnings. Refs #7789.
Fixed some doxygen warnings. Refs #7789.
Fixed a cppcheck warning. Refs #7789.
Fixed a doxygen error. Refs #7789.
Removed unused codes. Refs #7789.
Cleaned some logging.  Refs #7789.
Removed some unused declarations of methods. Refs #7789.