Add support for scoped parameters in extra_params

[jsmestad]

Background

Testing for missing values on a PUT request, it would be nice to have the following supported via extra_params with a example_request.

put '/users' do
  parameter :first_name, 'Users first name', scope: :user
  parameter :last_name, 'Users last name', scope: :user

  example_request 'with attributes', user: { first_name: 'John' } do
    status.should == 200
  end

  example_request 'without set attributes' do
    status.should == 422
  end
end

Currently this function is not "additive" but instead it overrides the entire user key with a new value. I am not sure if you want to use a different DSL for doing this sort of operation (like allowing some form of lets inside example_request blocks or a different syntax for specifying additive versus overwriting parameters).

Let me know what approach you'd like, as I am eager to contribute back to this awesome project!

[oestrich]

So this should work but might not work how you expect.

put '/users' do
  parameter :first_name, 'Users first name', scope: :user
  parameter :last_name, 'Users last name', scope: :user

  example_request 'with attributes', first_name: 'John' do
    # first name will be scoped inside user by #params
    params.should == { :user => { :first_name => 'John' } }
    status.should == 200
  end
end

If we can think of a way to make this more how you would expect it to work I'd definitely accept it.

[oestrich]

Closing because I think this was fixed with #182