nonlinearities.py: Fixed copy-paste error (rectify->identity)
nonlinearities.py: Fixed copy-paste error (rectify->identity)

DataFighter/Lasagne-tutorial,ebattenberg/Lasagne,DeanChan/Lasagne,ErnstHowie/Lasagne,Richi91/nntools,cancan101/Lasagne,mheilman/Lasagne,MihailoIsakov/fishfish,rlkelly/Lasagne,gabortakacs/Lasagne,dnuffer/Lasagne,kracwarlock/Lasagne