Fix model/view/controller methods to handle stringifiable objects

Fix model/view/controller methods to handle stringifiable objects

Previously, uri_for would test to see if its first argument was isa
Catalyst::Controller but then assume any other object was a Catalyst::Action;
this change uses Safe::Isa to check the class in both cases, which is useful
both for string overloading packages such as i18n.pm and HTML::String but also
when a Path::Class::File object is passed during static URI generation.