Fixed typo in 'image' property; now says 'VPGWCTenant' instead of 'VMMETenant'

Change-Id: Ic28d97d0f6ba39060e937c6373798bde2d498e08
diff --git a/xos/models.py b/xos/models.py
index f52a8ac..bfc43a0 100644
--- a/xos/models.py
+++ b/xos/models.py
@@ -190,7 +190,7 @@
         if img.lower() != "default":
             return Image.objects.get(name=img)
         else: 
-            return super(VMMETenant, self).image
+            return super(VPGWCTenant, self).image
 
     # Getter for the message that will appear on the webpage
     # By default it is "Hello World!"