Update test to be order-agnostic

[cbeer]

49. ActiveFedora::DatastreamCollections#named_datastreams_ids should return a hash of datastream name to an array of dsids
    Failure/Error: @test_object2.named_datastreams_ids.should == {"high"=>[], "thumbnail"=>["THUMB1", "THUMB2"]}
    expected: {"high"=>[], "thumbnail"=>["THUMB1", "THUMB2"]}
    got: {"thumbnail"=>[], "high"=>[]} (using ==)
    Diff:
    @@ -1,3 +1,3 @@
    "high" => [],
    -"thumbnail" => ["THUMB1", "THUMB2"]
    +"thumbnail" => []
    # ./spec/integration/datastream_collections_spec.rb:128:in `block (3 levels) in <top (required)>'