[NixIO] Check channel_ids when testing
[NixIO] Check channel_ids when testing

Tests fail now due to issue #356

JuliaSprenger/python-neo,theunissenlab/python-neo,INM-6/python-neo,rgerkin/python-neo,NeuralEnsemble/python-neo,samuelgarcia/python-neo,apdavison/python-neo