introduce platform specific defaults

pkg/config/config_default_platform.go

@@ -0,0 +1,10 @@
+// +build !windows !linux
+
+package config
+
+// GetPlatformDefaultConfig gets the defaults for the platform
+func GetPlatformDefaultConfig() []byte {
+	return []byte(
+		`os:
+  openCommand: 'open {{filename}}'`)
+}