Added generic confirm modal
Form modals will now prompt the user whether they want to discard changes if they click the backdrop (with a dirty form)
Merge branch 'develop' into feature/modal_dirty_dismiss

Conflicts:
	src/ggrc/assets/javascripts/controllers/modals_controller.js
Merge pull request #332 from reciprocity/feature/modal_dirty_dismiss

Clicking outside form modals will now warn the user prior to closing the modal (46021943)