Rewrite all tests to leverage new approach

[jwadolowski]

26 introduced totally new approach to test suites. Please rewrite all test suites in the same manner.

Remaining items from #26:

• [x] all tests need to be rewritten to include new properties (count, unique_fields, enforce_count, apply_all and include_missing). Additionally append changed its behaviour a bit (affects just array type properties), so it needs to be updated in all test cases (it's not that important anymore, as that's just for arrays)
• [x] update documentation in README.md file (properties and examples)
• [x] remove extisting test recipes
• [ ] update all serverspec test suites

[jwadolowski]

Test recipes were replaced by embedded test cookbooks in PR #52