use permitted_user_attributes to allow extension

Fixes #137
Use Spree::PermittedAttributes to set params allowed

This allow users to extend it whithout having to override that method.
e.g.

        Spree::PermittedAttributes.user_attributes.push :f_name, :l_name
Use PermittedAttributes in other controllers as well

Help users extend it better
support for the address persist stuff. Only merge in 2-1-stable when https://github.com/spree/spree/pull/4028 is merged in spree 2-1-stable
Clear out rails dynamic method deprecation warnings
Only require Core::UserAddress above Spree 2.1.3

Allow users on that version to run update this extension and run the
application without issues. e.g. unitialized constant Core::UserAddress