Support setting core number from python side (#1509)
Support setting core number from python side (#1509)

* support set core num

* fix session_config

* fix license

* address comments

intel-analytics/BigDL,intel-analytics/BigDL,yangw1234/BigDL,intel-analytics/BigDL,yangw1234/BigDL,yangw1234/BigDL,yangw1234/BigDL,intel-analytics/BigDL