Added email field to signup on login.php
Created CRUD functions in CRUD.php
Added CRUD.php to includes.php
Added readFromDB function (havent really tested yet).
Added addToDB function (havent really tested yet).

NOTE: We should only include connectDB.php where we need it to prevent too many unnecessary queries to database when they aren't needed.
Added changeInDB function in CRUD.php (untested)
Added removeFromDB function in CRUD.php (untested)