Implement simple basic auth for the exporter
Implement simple basic auth for the exporter

So this can be quickly thrown into public projects until better
methods of authentications are available

asbjornenge/client_golang,mattkanwisher/client_golang,KevinPike/client_golang,m3db/prometheus_client_golang,fabxc/client_golang,stapelberg/client_golang,jimmidyson/prometheus-client_golang,prometheus/client_golang,telendt/client_golang