aql/python: add some debugging info to queries

[adamstruck]

Addresses #129 on the client side. The query described in the issue is returned in a similar timeframe using either the python client or curl.

• Sets chunk_size to None in iter_lines method on response object.
  • chunk_size must be of type int or None. A value of None will function differently depending on the value of stream. stream=True will read data as it arrives in whatever size the chunks are received. If stream=False, data is returned as a single chunk. http://docs.python-requests.org/en/master/api/#requests.Response.iter_content
• Add debug logging to execute. See below. <Query instance>.execute(debug=True)

[DEBUG]    2018-08-01 10:50:13,692    POST http://arachne.compbio.ohsu.edu/v1/graph/bmeg/query
[DEBUG]    2018-08-01 10:50:13,694    BODY {"query": [{"v": []}, {"where": {"condition": {"key": "_label", "value": "Individual", "condition": "EQ"}}}, {"where": {"and": {"expressions": [{"condition": {"key": "source", "value": "tcga", "condition": "EQ"}}, {"condition": {"key": "disease_code", "value": "BRCA", "condition": "EQ"}}]}}}, {"in": ["sampleOf"]}, {"mark": "a"}, {"in": ["expressionFor"]}, {"render": ["$a.name", "$.expressions"]}]}
[DEBUG]    2018-08-01 10:50:13,695    STATUS CODE 200
[DEBUG]    2018-08-01 10:50:46,753    rate: 100 results processed (3/sec)
[DEBUG]    2018-08-01 10:51:17,131    rate: 200 results processed (3/sec)
[DEBUG]    2018-08-01 10:51:44,909    rate: 300 results processed (3/sec)
[DEBUG]    2018-08-01 10:52:11,921    rate: 400 results processed (3/sec)
[DEBUG]    2018-08-01 10:52:38,045    rate: 500 results processed (3/sec)
[DEBUG]    2018-08-01 10:53:03,918    rate: 600 results processed (3/sec)
[DEBUG]    2018-08-01 10:53:30,019    rate: 700 results processed (3/sec)
[DEBUG]    2018-08-01 10:53:56,306    rate: 800 results processed (3/sec)
[DEBUG]    2018-08-01 10:54:22,707    rate: 900 results processed (3/sec)
[DEBUG]    2018-08-01 10:54:48,587    rate: 1,000 results processed (3/sec)
[DEBUG]    2018-08-01 10:55:14,919    rate: 1,100 results processed (3/sec)
[DEBUG]    2018-08-01 10:55:19,348    rate: 1,116 results processed (22/sec)
[INFO]    2018-08-01 10:55:19,349    total: 1,116 results processed in 305 seconds

[kellrott]

I think this is some python3 specific syntax, and it broke the travis testing