v2.1

Notable additions and changes:

• Addition of the league leaders tab/page
• Addition of a search bar to search for any player and go to their player page
• Addition of the current matchup as the title in the navbar for a game
• Refractor of PlayerScreen.js to allow navigation from the selection in the league leaders table and from the player search
• Refractor of Boxscore.js
• Various improvements to the codebase suggested by CodeClimate