[manifest] Update for xwalk_launch_screen
[manifest] Crosswalk 8 on Android supports start_url

app.launch.local_path is deprecated on Crosswalk Android 8+
[manifest] csp replaces content_security_policy
[manifest] Make room for orientation page
[manifest] Make field-description page titles consistent
[manifest] Ensure fields are correct for Crosswalk 8
[manifest] Add xwalk_permissions field