Added verification before each battle

[tomcilo]

The problem can be seen while playing the HumanStrategy
The following scenario is possible

1. HumanStrategy is created and verified before the battles
2. We enter HP 100, 3 random moves, some random items
3. We pass verify
4. Before each of battles, new HumanStrategy is created, but not verified
5. We enter HP 10000000, 3 random moves, 9 cookies, 1 health pack (value > 500, which is the limit)
6. We battle with a clear advantage
   As a result players could make a good pokemon at first, but make a pokemon that wouldn't pass the verification (e.g. using a static variable)
   TL; DR
   One could make a pokemon that has virtually unlimited stats, all of the moves, and some items