fix themes names

plugins/theming.js

@@ -14,10 +14,10 @@ export default function (context) {
       case 'grey':
         context.$vuetify.theme.themes.light.primary = '#8c8c8c'
         break
-      case 'lightblue':
+      case 'light-blue':
         // already the default one
         break
-      case 'lightred':
+      case 'light-red':
         context.$vuetify.theme.themes.light.primary = '#dd453f'
         break
       case 'orange':