Increase test coverage

[ptrkkim]

Having been hacked together during hackathon, this project has no tests.
Confirm functionality and get practice writing tests in Jest/Enzyme:

Chat

• Rendering of messages
  • Plain messages
  • Parsing and rendering Emotes
• Functionality of chat input
  • Name validations
  • Custom chat commands
• Rendering of buttons and popovers
• Functionality of chat scroll-bar (conditional auto-scroll)

Game

• Game state changes properly on an interval
  • Reducer logic for moving the game character
  • Reducer logic for picking up items
• Chat commands are properly accumulated and follow majority-rules
• Assessing victory condition
• Rendering player count