Move minitests to rspec

This Branch moves *all* of the Minitests to Rspec. I checked the open pull requests and none of them touches the minitest files. So this should not create bad conflicts.

In order to make all specs pass, I already cherry-picked 527fefdad77ee24cde5825aaadedf4265da775aa from #1076 on top of this branch. This commit will be removed from this branch as soon as #1076 is merged into staging.




**Text before edit and rebase:** This Branch moves most of the Minitests to Rspec. The only ones I didn't touch are Ontology- and Oops-related because of some open pull request.

As travis shows, there are only 102 tests (173 assertions) left in Minitest.

In order to make all specs pass, I already cherry-picked 527fefdad77ee24cde5825aaadedf4265da775aa from #1076 on top of this branch. 


As of the latest "Translate *_spec to rspec." commits this branch should also fix #1044