Security hardening: fix possible shell injection vulnerability

The glance/cmd/control.py file contains a possible shell injection
vulnerability:

https://github.com/openstack/glance/blob/master/glance/cmd/control.py#L134 .

Setting 'shell=True' here opens the possibility of shell injection
by setting server to something like '; rm -rf /'. This will cause
the command 'rm -rf /' to be run with the privileges of the user
that ran Glance.

The fix is to parameterize the input so that the command run here
can only be 'logger'.

Change-Id: If48106ceea1dd582bcec9d03e056d88591bcba8d
Closes-bug: 1335208
Merge "Security hardening: fix possible shell injection vulnerability"