Also, change the `labels` to `label` for api consistency

* init commit

* change some dir name

* Adding support for the sigmoid_cross_entropy_with_logits operator

* Fixing a typo in the cuda file

* Adding Python documentation for sigmoid_cross_entropy_with_logits_op

* Correcting typos in documentation

* Adding unit tests for sigmoid_cross_entropy_with_logits_op

* Addressing code review feedback