Fixed functional test setup so that :controller and :action
are stored into path_parameters using string keys.
Added with_routing test helper which can be used to dynamically
replace the current set of routes inside a unit test.
git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@1763 5ecf4fe2-1ee6-0310-87b1-e25e094e27de