Fixed default region creation issue

If the default region did not exist, it is created,
but the previously created RGWDefaultRegionInfo object is not updated.
This fix updates this objects after the default region creation.
It was also preventing vstart.sh script to start with -r option.

Signed-off-by: Christophe Courtaut <christophe.courtaut@gmail.com>
Reviewed-by: Yehuda Sadeh <yehuda@inktank.com>