Remove old test code to support Rails 3.0
Remove old test code to support Ruby 1.8
Inherit from proper proxy/basic object to avoid deprecation warnings

Rails 4 deprecated BasicObject in favor of ProxyObject.
Remove support for passing extra options to assignment methods

Old mass assignment options like :without_protection are being killed in
Rails 4, so the 3.2.x compatibility is also dropping support for it in
favor of using things like strong parameters.