Add a proxy route for Grafana dashboards

[ghost]

Today's pair-programming session with @rpappalax.

[pdehaan]

:sad_trombone: Looks like the devilishly handsome @rpappalax merged my PR first and we got caught in a mid-air collision. Can you rebase this and I'll review+merge.

I shuffled the code around a bit, but the files you'll probably want to touch are:

• https://github.com/loads/loads-web/blob/master/server/routes/broker.js

... and then you can either just dump all the functions and handlers in the file itself, or create a ./server/controllers/dashboards.js file and dump makeMapFunc() function and module.exports the handler object.

Don't worry too much about the code organization, I can always shuffle and move it later.

[ghost]

@pdehaan No worries.

[pdehaan]

@kitcambridge, you magnificent bastard! :+1:

[rpappalax]

Thanks, hermanos