Change alerts/notice/errors color to rich blue.
Add UserFlag model, validations to UserFlag model, and flag button to user show view.
Add routes for create and destroy actions in user_flags controller, add create action, add method to pass custom validation error messages on redirect.
Tweak successful flagging notice.
Add PostFlag model.
Add post_flags controller and create action, validations to PostFlag model, routes for post_flag creation/destruction and flag button in post show view.
Fix errors in post_flags create controller action.
Add helper methods to govern display of flagging buttons, adjust styling.