seperate dashboard from binary

While it is nice to have a builtin way to get a dashboard out of the pcm process, I'd like to have it available in a standalone file as well.

I was going to add it to my grafana deployment process and document the origin via a commit hash. With the dashboard as its own file I can do something like: `source : https://github.com/intel/pcm/commit/ec686427572c2d22dab7ab182592649976b07be6/filename` to clearly identify the source and version of the chart.

I'd swear the dashboard was in its own set of `.json` files (one for prometheus, one for influxdb) in the past.