Fix unstable json.dumps ordering in obj-server test
Fix unstable json.dumps ordering in obj-server test

test_GET_HEAD_with_fragment_preferences seemed to fail on ocassion on
my machine; the test seemed to be assuming the order of dictionary
keys in json output sent in headers; the fix was convert back to a
dictionary when making the assertion on the context of the json.

Change-Id: I1ea1b734c2a9fb12b8f59262bb1229421803e48e
Closes-Bug: #1625956

nadeemsyed/swift,matthewoliver/swift,clayg/swift,swiftstack/swift,psachin/swift,redbo/swift,swiftstack/swift,notmyname/swift,clayg/swift,hurricanerix/swift,psachin/swift,openstack/swift,psachin/swift,notmyname/swift,tipabu/swift,swiftstack/swift,openstack/swift,tipabu/swift,openstack/swift,hurricanerix/swift,matthewoliver/swift,notmyname/swift,hurricanerix/swift,matthewoliver/swift,smerritt/swift,notmyname/swift,redbo/swift,nadeemsyed/swift,nadeemsyed/swift,openstack/swift,tipabu/swift,clayg/swift,smerritt/swift,tipabu/swift,hurricanerix/swift,psachin/swift,smerritt/swift,smerritt/swift,nadeemsyed/swift,matthewoliver/swift,clayg/swift