Eliminate OrderedDict from test_api_v2.py

Neutron cannot possibly be passing tests under Python 2.6, as
neutron/tests/unit/test_api_v2.py is referencing
collections.OrderedDict, which does not exist in Python 2.6.
Since there is no reason to use an OrderedDict in this case,
this replaces it with a simple dict.

Change-Id: I1b9886f508c4c8b96cf50c50f157c1960da433fc
Closes-Bug: #1372571
Merge "Eliminate OrderedDict from test_api_v2.py"