Implement notifications email/desktop

api/api.go

api/auth.go

api/db/db.go

api/db/db_test.go

api/db/notifications.go

api/db/notifications_test.go

api/db/preferences.go

api/db/preferences_test.go

api/mail.go

api/member.go

api/member_test.go

api/order.go

src/App.js

src/Head.js

src/Panel.js

src/notifications.js

src/preferences/Notifications.js

src/preferences/OwnPassword.js

src/preferences/PasswordForm.js

src/preferences/ResetPassword.js