Proxy Graphite calls

[aalpern]

See related: #419

The long term plan for Tessera is to re-write the backend in Go and add support for multiple time series DBs along the way, via a proxy layer that translates results to a single datapoint series format for the Tessera UI to use.

In the meantime, however, adding a few additional routes in the Flask code of the existing backend to proxy Graphite traffic can be done easily and will greatly simplify deployment and configuration, as the browser would no longer need to talk directly to Graphite, eliminating CORS configuration, having multiple ports and addresses accessible to the browser, etc....

OR

Get a better easy to use Docker image running nginx in front of tessera and graphite to accomplish the same thing with better performance.