This simply takes any json files present and loads them into Grafana
directly. The idea is that you can edit the dashboards using the
inbuilt editor, then copy the dashboard JSON and keep it externally
version controlled. No parsing or validation is done on the JSON
files; we are assuming they have not been hand-modified from what
Grafana generates.
Change-Id: I38695aed2404f8b7fc350d949b7a9212498c35cb
5f785f7782