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
the ability to turn on collapse was already there (yes this means you could break the search the way it sat before i touched it)  if you added AdvancedGroupingMode=true&EnableCompanyJobTitleCollapse=true to the query string it would turn on grouping.  Or in the gems case, if you include those in the hash that you send into the search API.