Allow examples.get call without data

It wasn't possible to call examples.get without a --data parameter. This
change checks if the opts.data is empty, and if so, just deals with it.

Change-Id: I262e8f8b061d163e478c3b9fe611a44180119909

examples/common.py

@@ -67,6 +67,8 @@ def find_resource_cls(opts):
 
 
 def get_data_option(opts):
+    if not opts.data:
+        return opts.data
     try:
         iddy = uuid.UUID(opts.data)
         return {'id': iddy}