IssueTracker

Please provide as much information as possible. At least, this should include a description of your issue and steps to reproduce the problem. If possible please provide a summary of what steps or workarounds you have already tried, and any docs or articles you found (un)helpful.

Problem you have encountered:
BlockType 'TABLE' is never returned from REST API I receive only TEXT
Attached one of the images i tried to get table from.

What you expected to happen:
To receive a BlockType TABLE

Steps to reproduce:
I run the default example on pyton:
```
    from google.cloud import vision
    client = vision.ImageAnnotatorClient()

    with io.open(path, 'rb') as image_file:
        content = image_file.read()

    image = vision.types.Image(content=content)

    response = client.document_text_detection(image=image)
```

Other information (workarounds you have tried, documentation consulted, etc):