courseware component for poll comparison table

cms key policy in advanced setting, using "poll_compare".
related files
are:cms\env\dev.py;common\lib\xmodule\setup.py;lms\djangoapps\courseware\module_render.py;cms\templates\widgets\poll_compare-edit.html;common\lib\xmodule\xmodule\css\poll_compare\display.scss;common\lib\xmodule\css\poll_compare\edit.scss;common\lib\xmodule\xmodule\js\src\poll_compare\edit.coffee;common\lib\xmodule\xmodule\poll_compare_module.py;lms\templates\poll_compare.html