CLI: Fix config flag being ignored

Passing --config had no effect when passed.  It will now be applied as
the last config file and before any env var overrrides.

pkg/setting/setting.go

@@ -164,9 +164,13 @@ func loadEnvVariableOverrides() {
 	}
 }
 
-func NewConfigContext() {
+func NewConfigContext(config string) {
 	configFiles := findConfigFiles()
 
+	if config != "" {
+		configFiles = append(configFiles, config)
+	}
+
 	//log.Info("Loading config files: %v", configFiles)
 	var err error