refactor(hoodieStore): add tests, more clarity

I wanted to add some unit tests for the hoodieStore refactor, and I also want to propose a different approach.

I think it's better to be explicit with which methods and properties to copy, so that only what is needed is copied over.

I wasn't sure what to do with the $rootScope.$emits, so I left them as is for now.

Let me know if anything else needs to be changed.

If we open lots of small PRs that only change one specific aspect, it will be a lot easier to merge the refactor.