Fix remaining refs to the former config object

Switch notation from

    value = d.key

to

    value = d.get('key') # in optional cases
    value = ['key'] # in required cases

Unittests for config dictionary make use of mock.patch.dict

Change-Id: Ib688dd13e1e3df9a82b3f0377064be8e6c765e55
Closes-Bug: #1301020