Revise `test_get_job_includes` and endpoint

What is the expected behavior?

The test_get_job_includes has been failing in a number of recent travis runs for the premium accounts:

  File "/home/travis/build/Qiskit/qiskit-ibmq-provider/qiskit/providers/ibmq/api/ibmqconnector.py", line 194, in get_job
    if ('result' in qasm) and ('data' in qasm['result']):
TypeError: argument of type 'NoneType' is not iterable

The endpoint has been slightly flaky for a while - we should investigate and coordinate with the API team for a proper solution, and ensure that:

• the endpoint is working for all environments + both old api and new api
• the test use the same and correct fields (for connector we use deleted, for client we use shots)
• the test also exercises include_fields
• the function handles unexpected cases gracefully (excluding/including non-existent fields, etc)

[jyu00]

get_job with include_fields=['status'] is now failing with a generic error for v1 api. It appears to be the only field failing, and exclude_fields['status'] works.

[diego-plan9]

Fixed via #380