Fix failures in python tests (#1623)
Fix failures in python tests (#1623)

* fix test failures in creating layers

* Fix wrong file path in save_graph_topology

* Fix lambda invalid syntax in python3.5
yangw1234/BigDL,yangw1234/BigDL,intel-analytics/BigDL,intel-analytics/BigDL,intel-analytics/BigDL,yangw1234/BigDL,intel-analytics/BigDL,yangw1234/BigDL