Add initial battle scene

I added the initial battle scene that is within the story. I imported some more default images and music.
Add Simple Battle and end condition

- A battle starts between Eileen and Lucy (same sprite for now)
- They can attack each other and move
- The Lucy sprite is controlled by a simple AI
- The win result is carried back to the story
Merge pull request #1 from inarizushi/simple-battle

Add a simple battle to the story