add CosineDistanceCriterion (#1195)
add CosineDistanceCriterion (#1195)

* add CosineDistanceCriterion

* add cosineDistanceCriterion

* add CosineDistanceCriterion python test

* add python test

* add blank line in pythonapi

* revise APIDocs

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