added loading graphic, and child_process, kill Rscript tasks so that the application cleans up the R Shiny Server and stops it from running
added loading graphic, and child_process, kill Rscript tasks so that the application cleans up the R Shiny Server and stops it from running

ColumbusCollaboratory/electron-quick-start,ColumbusCollaboratory/electron-quick-start,ColumbusCollaboratory/electron-quick-start,ColumbusCollaboratory/electron-quick-start,ColumbusCollaboratory/electron-quick-start,ColumbusCollaboratory/electron-quick-start,ColumbusCollaboratory/electron-quick-start,ColumbusCollaboratory/electron-quick-start,ColumbusCollaboratory/electron-quick-start,ColumbusCollaboratory/electron-quick-start,ColumbusCollaboratory/electron-quick-start