use rails helpers for resource routes

[phoffer]

I encountered some issues when using Rails scaffolding with a model name/namespace that didn't match up. Ie. scaffolding admin routes for some resources like this:

rails generate scaffold admin/user name:string --model-name="User"

This should generate everything using a User model, but with routing that follows admin_user* naming pattern. However, the templates would generate links with user* for paths.

This updates the templates to use the rest of the routing helpers Rails provides, and also includes a handler for the form target url, only if necessary.

[amatsuda]

@phoffer haml-rails gem now generates haml templates that are completely HTML-equivalent to the Rails' original ERB templates (see #197).
So, could you try haml-rails 3.0.0 and check whether your problem is solved? If not, maybe we should fix Rails first. Thank you for your patch anyway!