Red version 3.1 Compatibility

[NeuroAssassin]

This PR features 3.1 Compatibility (also contains backwards compatibility for 3.0.2), and two extra small messages that clarify some things.

List of changes:

• Casino:
  • Added cog_unload, which calls __unload
  • Change from get_user (as get_user can have issues)
  • Updated version number
• Jisho:
  • Added cog_unload, which calls __unload
• Race:
  • Added two messages to clarify why you couldn't do something when you called the command (I can remove this if needed)
  • Addresses #170
• Raffle:
  • Added fetch_message to a caught exception (x2)
  • Added cog_unload, which calls __unload
  • Fixed a spelling error
  • Updated version number
• Shop
  • Removed load_bundled_data in __init__.py, as it is deprecated

Extra Notes: This closes #170