vstart.sh: quote cmd params when display executing cmd

vstart.sh: quote cmd params when display executing cmd

vstart.sh will echo executed cmd to the stdout:

/root/jiaying/ceph/build/bin/radosgw -c /root/jiaying/ceph/build/ceph.conf --log-file=/root/jiaying/ceph/build/out/rgw.j.log --debug-ms=1 -n client.rgw --rgw_frontends=civetweb port=8000

As params contain whitespaces, pasting the above cmd into the shell didn't start rgw
on the port 8000. Now the vstart.sh output is like the following:

'/root/jiaying/ceph/build/bin/radosgw' '-c' '/root/jiaying/ceph/build/ceph.conf' '--log-file=/root/jiaying/ceph/build/out/rgw.j.log' '--debug-ms=1' '-n' 'client.rgw' '--rgw_frontends=civetweb port=8000'

We can paste above cmd to the shell to restart rgw, it's more convenient for debugging.

Signed-off-by: Jiaying Ren <jiaying.ren@umcloud.com>