added two test cases, which test without t_start or t_stop
added two test cases, which test without t_start or t_stop

mczerwinski/elephant,INM-6/elephant,mdenker/elephant,mczerwinski/elephant,pietroquaglio/elephant,sonjagruen/elephant,ccluri/elephant,neuroelectro/elephant,ccluri/elephant,dholstein/elephant,etorre/elephant,mdenker/elephant,apdavison/elephant,NeuralEnsemble/elephant,NeuralEnsemble/elephant,dholstein/elephant,alperyeg/elephant,lzehl/elephant,INM-6/elephant,carloscanova/elephant,NeuralEnsemble/elephant,btel/elephant,lzehl/elephant,btel/elephant,Junji110/elephant,Junji110/elephant,JuliaSprenger/elephant,pietroquaglio/elephant,mdenker/elephant,espenhgn/elephant,espenhgn/elephant,etorre/elephant,carloscanova/elephant,apdavison/elephant,INM-6/elephant,sonjagruen/elephant,neuroelectro/elephant,alperyeg/elephant