RF: Go down to 1.7.1
RF: Go down to 1.7.1

See: https://mail.python.org/pipermail/neuroimaging/2015-October/000536.html

JohnGriffiths/dipy,StongeEtienne/dipy,FrancoisRheaultUS/dipy,nilgoyyou/dipy,matthieudumont/dipy,villalonreina/dipy,nilgoyyou/dipy,FrancoisRheaultUS/dipy,villalonreina/dipy,demianw/dipy,JohnGriffiths/dipy,matthieudumont/dipy,demianw/dipy,StongeEtienne/dipy