Absolute imports in Viz
Absolute imports in Viz

Fixes https://github.com/nipy/dipy/issues/1007
matthieudumont/dipy,FrancoisRheaultUS/dipy,nilgoyyou/dipy,matthieudumont/dipy,StongeEtienne/dipy,villalonreina/dipy,StongeEtienne/dipy,nilgoyyou/dipy,FrancoisRheaultUS/dipy,villalonreina/dipy