Rename metrics constants to follow convention
Rename metrics constants to follow convention

so that we can scan for undocumented metrics.

Convention is that metrics should be a const ending in "Metric",
"Duration", "Count" or "Counter"

[#152440533]

Signed-off-by: Brandon Shroyer <d370be3f39cb88690ed16d1a7b77debc20949e86@pivotal.io>

cloudfoundry-incubator/rep