Added a functional menubar with logout, add new defect, and about menu items. Also added accompanying controller class.

This menubar is linked to the mainframe and independent of the mainmenu
panel. It only becomes visible after login. If we decide to keep this
menubar, we can scrap the menu buttons as they're no longer needed.
Merge branch 'master' of https://github.com/SobaDeveloper/DefectTracker