Add changing status icon in example

Add changing status icon in example

to test this, you need to add a conf file under /etc/dbus-1/session.d/

<?xml version="1.0"?>
<!DOCTYPE busconfig PUBLIC "-//freedesktop//DTD D-BUS Bus Configuration
1.0//EN"
        "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">
<busconfig>
        <policy context="default">
                <allow send_destination="org.agl.homescreen"/>
        </policy>
</busconfig>

Change-Id: I82c4b01db86ee54de87fad1db2ebf3f743b7c020
Signed-off-by: Tasuku Suzuki <tasuku.suzuki@qt.io>