Serializing of deeply nested presenter exposures

[marshall-lee]

it 'serializes deeply nested presenter exposures' do
  e = Class.new(Grape::Entity) do
    expose :y
  end
  subject.expose :a do
    subject.expose :b do
      subject.expose :c do
        subject.expose :lol, using: e
      end
    end
  end
  expect(subject.represent(lol: { y: 123 }).serializable_hash).to eq(
    a: { b: { c: { lol: { y: 123 } } } }
  )
end

Now fails with:

       -:a => {:b=>{:c=>{:lol=>{:y=>123}}}},
       +:a => {:b=>{:c=>{:lol=>#<#<Class:0x00000003a499c8>:0x00000003a3f0b8 @delegator=#<Grape::Entity::Delegator::HashObject:0x00000003a3f090 @object={:y=>123}>, @object={:y=>123}, @options={:root=>nil, :only=>nil, :except=>nil}>}}},

Will be fixed in #151.