Invert PercentCommand when 'invert_percent' option is true.

The 'invert_percent' option was only used in handleEvent() Method.
Use this option also for Commands sended to an ZWave Rollershutter.

Tested with Fibaro FGRM222 Roller Shutter.
Merge pull request #1297 from jo-we/zwave-rollerShutter-invertPercentCommand

[Z-Wave] Invert PercentCommand when 'invert_percent' option is true.