Bump nats gem to latest version

Signed-off-by: Matthew Sykes <matthew.sykes@gmail.com>
Do not send metrics with no value [#74567060]

Signed-off-by: Johannes Tuchscherer <jtuchscherer@pivotallabs.com>
Remove unused received_requests metric from router handler

Signed-off-by: Johannes Tuchscherer <jtuchscherer@pivotallabs.com>
Always set the Collector::config before each test-case run.