Collapse job search

this adds the ability to handle collapsed job searches to the ruby api gem.  If collapse is off it will handle everything as it used to. But if collapse is on, it will go down the collapsed path and return a Cb::Models::CollapsedJobResults insted of a Cb::Models::JobResults
You set `search` the same in both tests, so I might move this to a `let` block. And there's a variable set in the `before` block, so I'd move that to a `let` as well. And you want to try and limit yourself to one assertion per test. Something like this:
``` ruby
context 'blah' do
  let(:search) { Cb.job.search(Hash.new) }
  let(:content) do
    {
      ResponseJobSearch: {
        # etc
      }
    }
  end

  before do
    stub_request(:get, uri_stem(Cb.configuration.uri_job_search)).to_return(:body => content.to_json)
  end
  
  it { expect(search.model).to be_a Cb::Models::CollapsedJobResults }
  it { expect(search.model.grouped_jobs[0].job_description).to be_a Cb::Models::Job }
  it { expect(search.model.grouped_jobs[0].grouping_value).to eq '123321' }
  it { expect(search.model.grouped_jobs[0].job_count).to eq 1 }
  it { expect(search.model.grouped_jobs[0].job).to eq search.model.grouped_jobs[0].job_description  }
end
```