Fix for issue 56 on button theme changing
Removed spurious default color settings and check for changing in background_color to update _current_button_color. Fix for https://gitlab.com/kivymd/KivyMD/issues/56.
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
Removed spurious default color settings and check for changing in background_color to update _current_button_color. Fix for https://gitlab.com/kivymd/KivyMD/issues/56.