feat: configure dnscluster to allow multi-node

* Configure `docker-compose` to scale at least 2 nodes.
* Add script to start service with proper naming
* Create custom resolver.
  * This is not strictly necessary.

config/dev.exs

@@ -1,5 +1,9 @@
 import Config
 
+config :wabanex,
+  dns_cluster_query: :ignore,
+  dns_cluster_resolver: Wabanex.DevDNSClusterResolver
+
 # Configure your database
 config :wabanex, Wabanex.Repo,
   database: "wabanex_dev",

config/runtime.exs

@@ -1,5 +1,7 @@
 import Config
 
+config :wabanex, dns_cluster_query: System.get_env("DNS_CLUSTER_QUERY") || :ignore
+
 config :wabanex, Wabanex.Repo,
   username: System.get_env("POSTGRES_USER") || "postgres",
   password: System.get_env("POSTGRES_PASS") || "postgres",