changed add employee and fixed gui inconsistencies

...pp/src/main/java/com/example/schedulerapp/Controller.java

...ulerApp/src/main/java/com/example/schedulerapp/Model.java

.../main/resources/com/example/schedulerapp/addEmployee.fxml

...ces/com/example/schedulerapp/availabilityBottomPanel.fxml

...main/resources/com/example/schedulerapp/editEmployee.fxml

...in/resources/com/example/schedulerapp/employeeHeader.fxml

...es/com/example/schedulerapp/employeeSchedBottomPanel.fxml

...ain/resources/com/example/schedulerapp/headerManager.fxml

...ces/com/example/schedulerapp/schedBottomPanelManager.fxml

...in/resources/com/example/schedulerapp/schedSidePanel.fxml

...urces/com/example/schedulerapp/staffManagerSidePanel.fxml