Restore admin role to ceilometer user.

Fixes bug 1193004

The ceilometer user needs the admin role, so that the resources
(instances etc.) associated with all tenants are visible to the
ceilometer agents for metering purposes.

Change-Id: I4d8a88d2d88a11a4b408e0c68ef227ec2af2d822
Merge "Restore admin role to ceilometer user."