Fix button and img visibility before model

Signed-off-by: Justin Georgi <justin.georgi@gmail.com>

modules/glmv.js

@@ -1,6 +1,10 @@
 let slideShowInterval = null
 let grabHotspot = null
 
+modelLoaded = function() {
+    $('.awaiting-model').css('display', 'flex').removeClass('awaiting-model')
+}
+
 /**
  * Sets listener and attributes on model-viewer to
  * allow for click registering of a new hotspot