GUI: Javascript cleanup and additional utility functions.

Change-Id: Ia16dd7eecedfd116e9d0a65d60d724657e87b8d3
diff --git a/web/gui/src/main/webapp/app/onos.css b/web/gui/src/main/webapp/app/onos.css
index b82a6e5..0a6cd90 100644
--- a/web/gui/src/main/webapp/app/onos.css
+++ b/web/gui/src/main/webapp/app/onos.css
@@ -59,7 +59,7 @@
     color: #CE5650;
 }
 
-#eegg {
+.centered {
     position: fixed;
     top: 50%;
     left: 50%;