Add ability to test model against Reclass source code

Related-bug: PROD-21847

Change-Id: I455e733ac7473d210c90261fefdf7dc2142e0b9b
diff --git a/src/com/mirantis/mk/Common.groovy b/src/com/mirantis/mk/Common.groovy
index 54eb85a..95a96c3 100644
--- a/src/com/mirantis/mk/Common.groovy
+++ b/src/com/mirantis/mk/Common.groovy
@@ -888,7 +888,7 @@
 
 /**
  * Ugly processing basic funcs with /etc/apt
- * @param configYaml
+ * @param configYaml YAML text or Map
  * Example :
  configYaml = '''
  ---
@@ -907,7 +907,12 @@
  */
 
 def debianExtraRepos(configYaml) {
-    def config = readYaml text: configYaml
+    def config = null
+    if (configYaml instanceof String) {
+        config = readYaml text: configYaml
+    } else {
+        config = configYaml
+    }
     if (config.get('repo', false)) {
         for (String repo in config['repo'].keySet()) {
             source = config['repo'][repo]['source']