Support the minimal p8s metric text format

[pilhuhn]

The current code seems to expect that each metric is prefixed with a # TYPE line as in

# TYPE http_requests_total counter
http_requests_total{method="post",code="200"} 1027 1395066363000

P8s allows to skip the # TYPE as in

# Minimalistic line:
metric_without_timestamp_and_labels 12.47

We should support that.

[jmazzitelli]

We are using the official prometheus client from prometheus.io to read prometheus endpoints. We should make sure the problem isn't in that third-party client library code.

But without the #TYPE line, we don't know what the type of the metric is (counter or gauge) so if the endpoint does NOT provide that, the user must provide the "type: " field in the endpoint YAML within the configmap.