irate is a rate function that only looks at the most
recent two data points, and calucaltes a per-second value
from that. This produces much more granular graphs for
fast moving data, and works sanely across many scrape intervals.
It doesn't do so well for slowly moving data.
This provides the basic js, css and console template
templates required to build dashboards.
Included as an example are consoles for the node_exporter.
Change-Id: I4cfeea5e9691a9413f74ae98ca32a908df8e4a59
