Dockerize select hpfeeds tools

adds Dockerfile and init script as entrypoint to docker container

The following commands can be run on this container:
  docker run -d --name broker --link mongo:mongodb -p 10000:10000 pnelson/hpfeeds broker
  docker run --rm -ti --link mongo:mongodb pnelson/hpfeeds add_user MyUser MySecret geoloc.events snort.alerts
  docker run --rm -ti --link mongo:mongodb pnelson/hpfeeds dump_users
  docker run -d --name geoloc --link broker:broker -v /srv/geo:/opt:ro pnelson/hpfeeds geoloc

Running the image with no additional parameters prints a help message describing how to use it
  docker run --rm -ti pnelson/hpfeeds