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.
Fix up typo: $module->name --> $module_name
Add a comment to explain why we only load some of our 3rd party modules.
Update the test path to work with K3.
Database::set_default_instance() is no longer necessary.
DB::update()->set() API changed.
Add purifier and image to the 3rd party module list.
DB::insert() API changed.
URL::current() went away - keep our version of it but make it work with the new K3 APIs.
Partway through getting the unit test controller working.
Merge pull request #298 from shadlaws/args_20130417

Add args functionality to Controller and Request.