Enhancement: expose current_resource_owner to views

[vlad-pisanov]

Just as Devise makes current_user accessible to both the controllers and views via helper_method, it would make sense to make current_resource_owner accessible to views as well.

Currently, when custom views need to access the resource owner, it must be done via the hacky and undocumented @current_resource_owner memoized variable.

[nbulaj]

Hey @vlad-pisanov . Makes sense for me, do you want to propose a PR?