Moved some config over to an actual config file, improved error handling

config/config.example.toml

@@ -0,0 +1,5 @@
+[mqtt]
+host="example.com"
+port=1234
+username="username"
+password="password"

config/zeus_dev.toml

@@ -0,0 +1,4 @@
+[mqtt]
+host="olympus.lan.huizinga.dev"
+port=8883
+username="mqtt"