SPFA-167 SPFA-166 implementation of guess api and code refactoring

[directnrg]

• implemented code refactoring to use middleware functions and avoid code repetition.
• fixed delete methods that where not executing correctly for games and guesses.
• deleted unecessary files.
• updated league model to implement a validator for max amount of users per league. set to 7.
• implemented guess api. closes #31