Add a gitsync option for reverting to the commit used when building the image.
Add a gitsync option for reverting to the commit used when building the image.

brunostein/pfsense,NOYB/pfsense,NOYB/pfsense,ptorsten/pfsense,dennypage/pfsense,NewEraCracker/pfsense,brunostein/pfsense,dennypage/pfsense,phil-davis/pfsense,pfsense/pfsense,phil-davis/pfsense,ptorsten/pfsense,NewEraCracker/pfsense,ch1c4um/pfsense,NOYB/pfsense,BlackstarGroup/pfsense,BlackstarGroup/pfsense,phil-davis/pfsense,ch1c4um/pfsense,BlackstarGroup/pfsense,NewEraCracker/pfsense,NewEraCracker/pfsense,pfsense/pfsense,ch1c4um/pfsense,brunostein/pfsense,ch1c4um/pfsense,dennypage/pfsense,phil-davis/pfsense,jxmx/pfsense,jxmx/pfsense,pfsense/pfsense,BlackstarGroup/pfsense,pfsense/pfsense,ptorsten/pfsense,jxmx/pfsense,dennypage/pfsense