Fix ec2 CreateVolumes/DescribeVolumes status

In admin context CreateVolumes/DescribeVolumes returns
extraneous information such as project_id, host, instance
data etc. This results in output which is not compatible
with the ec2 API. This change removes the addition
of the extra information.

This only partially fixes bug #1074901 as mapping the internal
volume states to ones specified by the ec2 api results in the devstack
euca.sh exercises to fail. But that can't be fixed until the fix
in this patch is through as the extraneous information returned by DescribeVolumes
causes euca-describe-volumes to not to show the attachment state for
a volume which is needed by the euca exercises.

Change-Id: I48a96fbfe4bb2e3da9514d688638ecdf3a168303
(cherry picked from commit c62d7636b6ba1c36a96119a87fff8495c5a1dc21)