Add tests

[OleksiyRudenko]

Test level 1 (literal objects)

Requires exported functions with pre-defined signatures to

1. create general object presentation for required
2. create presentation of props that are not required for item 1

Have at least 2 predefined objects that use different order of keys.

Require particular order of props and each prop tagged like `legs: xx; `

Test level 2 (classes)

Requires all classes exported. Uses Inhabitant, Dog, Cat, Human.

Requires properties (legs, hands, paws, name, species, breed, friends, gender -- as per pets vs humans)

Set of "silent" props is assigned randomly per student. Silents some are for humans, other for pets, and shared. Props are tested as well.

Classes are expected to have methods:

• toString (general presentation)
• hasTail (all classes; humans shouldn't have tail prop)
• getBreed (only pets)
• getFriends (returns array)

Integrity checks

Test cases and pre-defined code (except for implementation templates) should not be changed. Checksums? No commit intervening into those files?