extra_params use Hash#deep_merge! instead of merge

[jsmestad]

This allows support for this use case:

post '/post' do
  parameter :title, 'Title of post', scope: :post
  parameter :author_id, 'Integer of author', scope: :post

  let(:title) { 'My First Post' }
  let(:author_id) { '8' }

  example_request 'returns successful' do
    expect(response_body).to have_key(:id)
  end

  example_request 'fails with malformed id', post: {author_id: 'asdf'} do
    expect(response_body).to have_key(:errors)
  end
end

Before this change the params changes from post: {title: 'My First Post', author_id: 'asdf'} to post: {author_id: 'asdf'}. Hash#deep_merge! resolves this.

[oestrich]

Awesome, didn't know about deep_merge. Can you add a test for this? I'll go ahead and merge it after that.

[jsmestad]

@oestrich I think I still have one issue I need to resolve. Let me verify and I will ping you when its 👍

[jsmestad]

@oestrich alright this one should be good to go. The issue I was hitting is reported in #183 if you can look at that as well, but its unrelated to this patch.

[jsmestad]

@oestrich spec added to verify working order. I did discover that extra_params method did not handle the case where v is a Hash and not a direct value. That is fixed as well.

👍

[oestrich]

Looks good. Thanks!