Merge branch '8.x-3.x' into push-cron

* 8.x-3.x:
  Adds back in exception code to salesforce_mapped_object_load_multiple()
  Add a missing “}” to RestResponse
  string to bool
  restore caching on record type id query and return SFID object
  by aaronbauman - further iteration on objectifying REST API - Add Describe response class - Drop Upsert response class (upsert returns an SFID) - add __get to base response class and simplify child classes
  by aaronbauman - Standardize responses across some key REST endpoints and start working towards a framework for better extensibility in the REST layer.