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
I could go both ways. Being explicit is always good, but these params should be noted on the docs site. Also, there are no params at all exposed for job search, this wrapper method expects you to go to the docs site and pass in a hash of everything you want. So, all that in mind, I think I just convinced myself that I'm personally ok with the hash-as-arg way. If anyone is vehemently opposed speak up and make a case :)