Refactor duplicate logic, make request url helpers into private methods

There was duplicate logic in searchByAddress and searchByPhone to loop through results from Search/Textsearch and make follow-up Detail requests. I moved that logic into a separate helper function as a private method, since it shouldn't be able to be called by itself (yet). While I was going hog-wild on private methods, I also made _makeRequest and _generateUrl into private methods since it really doesn't make sense for them to be called independently either.