Make Reset button presence and behavior consistent across apps

Note that the Reset button is missing from GMvR, but the other two GMM apps have it. When present and clicked, it resets the input parameters. This updates the Parameter Summary panel, but the plot does not update to reflect the 'new' values. I think the plots should actually reset to empty as if someone has just loaded the app. I think it would be useful to have the Reset button on all apps, so consider adding it to the non-GMM plotting apps as well.