* Add priority queue to sdk

* fix issue of storing pointers and now copy

* update to use copy structure

* Remove file, put Item struct def. into other file

* add link

* clean up docs

* refactor internal data structure to hide heap method implementations. Other cleanup after feedback

* rename PushItem and PopItem to just Push/Pop, after encapsulating the heap methods

* updates after feedback

* refactoring/renaming

* guard against pushing a nil item

* minor updates after feedback

* Add SetCredentials, GenerateCredentials gRPC methods to combined database backend gPRC

* Initial Combined database backend implementation of static accounts and automatic rotation

* vendor updates

* initial implementation of static accounts with Combined database backend, starting with PostgreSQL implementation

* add lock and setup of rotation queue

* vendor the queue

* rebase on new method signature of queue

* remove mongo...