Safrs

* caching & instance-level permission check
* accept attributes for clinet-generated ids (72)
* improved default filtering, by SergioSoldado
* pass flask_restful method_decorators from expose_object
* fix bug in include parameter handling, reported by Matt Leiter

* Remove a debug print from v2.9.2
* Some minor fixes

* Improved performance
* Fix pagination bugs (70, 71)

* _s_delete
* use _s_parse_attr_value return value for patch

* HTTP Patch return 200
* Empty many-to-many relationships return `[]` instead of `null`
* Strict `include=` checking (return 400 in case of non-existing relationship)

* fix relationship sorting & filtering
* fix type json type coercion (by polyatail)
* http delete swagger response codes