Today if you want to pick up configuration changes in your Nomad clients or servers, you need to SIGHUP the agent. This is fine if you've got configuration management running that is replacing files and can reload the agent. But it's less useful if you want to force a client to fingerprint reloadable fingerprints, or if you want to stage updated configuration files across the cluster before reloading.

Let's add an Agent Reload API, that allows cluster admins to reload the agent's configuration identically to SIGHUP by calling the Agent.Reload() method. We'll want to gate this operation behind ACLs, of course... most likely with agent = "write" permissions.