Slot Machine Version 0.3

- Added new buttons & functionality for:
- Bet 10, 100, 1000
- Reset
- Added GUI text elements for:
- Credits
- Bet
- Jackpot
- Background updated to hold new GUI elements
- New reel images
- including source image
- Changed Banana to Watermelon
- Updated Description
- Changed caption
- Changed some local variables to Global Constants, as they never change
- Changed some variable names
- eg. 'playerMoney' to 'credits'
- Minor revisions to impoted file: Buttons.py