Throwing an exception incase the template service couldnt register template.

Author: karuturi

server/src/com/cloud/template/TemplateManagerImpl.java

@@ -384,7 +384,7 @@ public GetUploadParamsResponse registerTemplateForPostUpload(GetUploadParamsForT
 
             return response;
         } else {
-            return null;
+            throw new CloudRuntimeException("Unable to register template.");
         }
     }