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
what do you think about this?
```ruby
        let(:content) do {
          ResponseJobSearch: { GroupedJobSearchResults: { SearchResults: {
            JobSearchResultsGroup:[
              {
                NumberJobsInGroup: 1,
                GroupingValue: "123321",
                GroupedSearchResults: {JobSearchResult: {}}
              }
            ]
          }}}
        }
```