Tests that check the full list of todo items are no longer order dependant

In order to reduce the number of failures for implementations that prepend rather than append items, the tests that check the full list of todo items are no longer order dependant. There is now a single test that checks this requirement:

'should append new items to the bottom of the list'

As a result RiotJS #798 now has just 5 failures as opposed to 13, making the test results much clearer.