Fixed a bug where isManager wasn't properly evaluated, and changed how positions in the employee are separated.

Added functionality for availability and requesting time off to the app. The app needs at least one employee in the database to run. Make sure to open the sql file in the repo drop your current table and execute everything from "create database" to the end of the availability table.

Employees table now captures the email, phone number, isManager, and wage.
Shift table now captures the availability of the shift. Updated parsing so all employee and shift details are separated by commas.

Implemented Employee class to make it easier to get employee data, handle changes to database, and for testing.