#5 Migrate to go modules

I was having problems getting the binaries to work with our bitbucket - errors from the vendor git library. To solve this, I've created https://github.com/bruce34/grafana-dashboards-manager as a clone of this repo (forked from github, brought up to date). I'll start putting other changes we require in my own github area. My git/module-fu is currently lacking, but it seems work. Thanks.