Updated openstack/openstack
Project: openstack/ceilometer  6eac31861268e282b96eb5b5c5d2b20fd7e660a8

Add __repr__ method for sample.Sample

sample.Sample has no string format method, which will cause useless
message when print log.

Change-Id: I8b9863a4ac6ee3373e18d36681fbfc4c89732111
Closes-Bug: #1386187