* Control metricsWindow from root of app
- Add buttons [currently hidden] on metrics pages to control window of metrics requests
- Consolidate metricsWindow usage (stop passing it around)
- Add a ConduitLink component so we can stop passing around pathPrefix
- Add tests for ApiHelpers
* Hide the time window buttons; fix bug in absolute links
* Add a note explaining why metricWindow buttons are disabled
* Convert ConduitLink in to a component that wraps another