Close more open connections in tests

- Found some Eve app not assigned to self.app. They weren't cleaned up.
- In media tests, the media element needs to be removed due to the
  GridFS keeping a connection there.

Special attention in this patch to: `def test_cursor_extra_find(self):` I found a reference leak there, so one database connection wasn't cleaned. Why exactly I don't know, but I removed the `forced bind` (where a method is bound with self) and the problem was resolved. :confused: