create common configuration format interface

cnf/common.go

@@ -0,0 +1,20 @@
+package cnf
+
+// Field generic representation (root, branch or leaf)
+type Field struct {
+	// Label of the current field
+	Label string
+	// Value of the current field
+	Value string
+	// Children of the current field or NIL if none
+	Children []Field
+}
+
+// ConfigurationFormat is the common interface for all configuration parser
+type ConfigurationFormat interface {
+	// Get the value of a field if it exists
+	Get(string) (string, bool)
+
+	// Set the value of a field if exists
+	Set(string, string) bool
+}