Design how we structure the tests

[PaulQbFeng]

So far we test everything everywhere all at once wink wink.

We need to define some standards:

• in tests/champions/{name.py}What should be the minimum to test accross all champions. (stats + spell damages lvl 1 - 11 - 16 without items ?)
• Create a test per item like champions ?

So far I think those files should be refactored:

• all files in champions
• test_champion.py
• test_item.py (to remove ?)
• test_spell.py?