Arvados

In order to run, crunch-dispatch-slurm requires the usual ARVADOS_API_HOST and ARVADOS_API_TOKEN environment variables set. Additional configuration goes in /etc/arvados/crunch-dispatach-slurm/config.json. This means that the typical install requires writing two files: a configuration file for the init system to set the environment variables, and then config.json for other options.

Teach crunch-dispatch-slurm to read the API hostname and token from config.json [configuration names TBD]. Update the Install Guide to point users to doing all configuration there. This will simplify crunch-dispatch-slurm administration.