Add Warrior class and modules

- `Warrior` class holds the `RubyWarrior::Turn` instance and works with it
- `RubyWarrior::Turn` instance store in `Warrior` instance must be updated every turn
- `Warrior::Health` module holds health related methods
- `Warrior::Sight` module holds sensory related methods
- `Warrior::Brains` module will hold most logic methods, when Warrior becomes smarter
- Removed all logic from `Player#play_turn`, which was turning quite hugly