BUG: Retriever format not matching what reader is expecting

[mansilla]

Hello, first of all. Thank you for this wonderful project.
So, I'm following this tutorial here. But I'm having the following error:

Traceback (most recent call last):
  File "haystack_test.py", line 46, in <module>
    prediction = finder.get_answers(question="What is the mass of the electron?", top_k_retriever=10, top_k_reader=5)
  File "/Users/admin/miniconda3/envs/legy/lib/python3.6/site-packages/haystack/finder.py", line 55, in get_answers
    len_chars = sum([len(d.text) for d in documents])
  File "/Users/admin/miniconda3/envs/legy/lib/python3.6/site-packages/haystack/finder.py", line 55, in <listcomp>
    len_chars = sum([len(d.text) for d in documents])
AttributeError: 'list' object has no attribute 'text'

That line is actually only for printing info. But if I skip that, below in the same file haystack/finder.py, in line 61 the reader is invoked with the same documents objects and throws an error:

Traceback (most recent call last):
  File "haystack_test.py", line 46, in <module>
    prediction = finder.get_answers(question="What is the mass of the electron?", top_k_retriever=10, top_k_reader=5)
  File "/Users/admin/miniconda3/envs/legy/lib/python3.6/site-packages/haystack/finder.py", line 61, in get_answers
    top_k=top_k_reader)
  File "/Users/admin/miniconda3/envs/legy/lib/python3.6/site-packages/haystack/reader/farm.py", line 221, in predict
    "text": doc.text,
AttributeError: 'list' object has no attribute 'text'

So my conclusion is the format the reader is expecting is different from what the retriever is returning.

NOTE: I installed the library from GitHub as recommended in the Readme file.

[mansilla]

Closing since is the same as #68