This is to add a helper function to base controller resource class
for detecting whether a list of documents has any empty (None)
or non-object entries in it (since all documents should be
objects), resulting in a 400 Bad Request getting raised.
This is to prevent the following stacktrace from occurring:
File "/usr/local/lib/python3.5/dist-packages/falcon/api.py", line 244, in __call__
responder(req, resp, **params)
File "./deckhand/policy.py", line 104, in handler
return func(*args, **kwargs)
File "./deckhand/control/buckets.py", line 58, in on_put
documents, data_schemas, pre_validate=True)
File "./deckhand/engine/document_validation.py", line 387, in __init__
raw_document[prop] = document.get(prop)
AttributeError: 'NoneType' object has no attribute 'get'
Change-Id: I76fc9b0d7662358f8b26b5bddf1187e92d1554de
04ad3fa93b