* Add find_unused_parameters option

As unused parameters in modules may not be expected sometimes, 
add an explicit error msg when it occurred and an option to avoid the error: https://github.com/microsoft/DeepSpeed/issues/707

* Add find_unused_parameters option

As unused parameters in modules may not be expected sometimes, 
add an explicit error msg when it occurred and an option to avoid the error: https://github.com/microsoft/DeepSpeed/issues/707

* Fix syntax error

* Fix yapf error

* Fix yapf error

* Fix yapf error

* Fix yapf error

* Move stage2 find_unused_parameters to config file

* Add stage2 find_unused_parameters

* Add stage2 find_unused_parameters

* Add stage2_find_unused_parameters option

* Change error msg to reflect zero_optimization config change

* Fix yapf error

* Fix yapf errors

* Change find_unused_parameters option name

* Change find_unused_parameters option name

* Change find_unused_parameters option name

* Change find_unused_parameters option name

* Change find_unused_parameters option name

* Add UnusedParametersModel for test option find_unused_parameters

* Add unit test for stage2 find_unused_parameters

* Add cpu-adam compatible check

* Remove dups import

* Trim spaces

* Fix yapf errors

* Trim spaces

* Add False Positive test check

* Fix find_unused_parameters test

* Trim spaces

* Fix yapf error