GUAC-897 Using a spinner instead of a distracting modal.

guacamole/src/main/webapp/app/index/styles/status.css

@@ -109,3 +109,14 @@
 .shown .status {
     visibility: visible;
 }
+
+.loading {
+    background-image: url(images/spinner.gif);
+    background-position: center;
+    background-repeat: no-repeat;
+    min-height: 200px;
+}
+
+.loading * {
+    visibility: hidden;
+}