Add edit page, dialog based item page. Consider switching to popups.

inventory/pages/__init__.py

@@ -1,6 +1,7 @@
 from .root_page import RootPage
-from .about_page import AboutPage
+from .settings_page import SettingsPage
 from .add_page import AddPage
+from .add_location import AddLocationPage
 from .browse_page import BrowsePage
 from .login_page import LoginPage
 from .item_page import ItemPage