Added test case for spike_extraction
Added test case for spike_extraction

mdenker/elephant,ccluri/elephant,etorre/elephant,carloscanova/elephant,NeuralEnsemble/elephant,NeuralEnsemble/elephant,INM-6/elephant,alperyeg/elephant,etorre/elephant,apdavison/elephant,carloscanova/elephant,alperyeg/elephant,mdenker/elephant,apdavison/elephant,NeuralEnsemble/elephant,pietroquaglio/elephant,ccluri/elephant,INM-6/elephant,JuliaSprenger/elephant,mdenker/elephant,pietroquaglio/elephant,INM-6/elephant