Test struct

I did several things here, would you to review.

1. Simplified test folder structure. I see that `plain` structure for tests works much better than `trees`. I could assume if project gets really big, `tree` structure could have more benefits.
2. Renamed all tests from `Spec.js` to `.spec.js` - that would work a bit better.
3. Removed `symbiosisSpec.js` as it tests actually nothing, all aspects of ORM will be covered by corresponding tests.