Meter widget is implemented with GaugeMeter (https://github.com/Mictronics/GaugeMeter). GaugeMeter provides a number of parameters to customize its display. See https://github.com/Mictronics/GaugeMeter#parameter-definitions for details.
Allow user to customize GaugeMeter by setting the customization parameters in the result.
This mechanism can be used to show actual values instead of percentages by setting total, used & showvalue parameter in the result.
Fixes#428
