Add args functionality to Controller and Request.
- add Request::arg() to get, clean, and return args from Request::param().
- add Controller::arg() as alias of Request::arg()
- add Controller::arg_required() to get arg or throw HTTP 400 if missing/invalid.
- revise bootstrap to include args in the routes.
Merge pull request #298 from shadlaws/args_20130417

Add args functionality to Controller and Request.