throw filenotfound exceptions

The system classes will throw a file not found exception if it cannot
find a file at the specified path.
the filter works

Now you can filter by completion status
Works by calling GetCompleted, GetPending, or GetAll on a JobController,
and passing that list to the update list box function
adding an employee is totally smooth

BUT when it goes to the file, it's all 0s for employee
Jobs now display correct employees

the problem was primarily in the fromString function of JobSystem, which
used the old constructor (which didn't care about employees)
employee listbox updates after add new

add a formclose listener to the AddNewEmployeeUI. when that windows
closes, the listbox on the DisplayEmployeeListUI updates.