Fixed waitForMinion functionality in Salt.groovy

Change-Id: I46c2fccb262ab9698a0fc822cd339db414a164e8
diff --git a/src/com/mirantis/mk/Salt.groovy b/src/com/mirantis/mk/Salt.groovy
index b71bf2f..5973184 100644
--- a/src/com/mirantis/mk/Salt.groovy
+++ b/src/com/mirantis/mk/Salt.groovy
@@ -796,7 +796,8 @@
                                 resKey = k
                             }
                             resource = node[resKey]
-                            if(resKey.contains("salt_minion_service_restart") && resource instanceof Map && resource.keySet().contains("result")){
+                            // try to find if salt_minion service was restarted
+                            if(resKey instanceof String && resKey.contains("salt_minion_service_restart") && resource instanceof Map && resource.keySet().contains("result")){
                                 if((resource["result"] instanceof Boolean && resource["result"]) || (resource["result"] instanceof String && resource["result"] == "true")){
                                     if(resource.changes.size() > 0){
                                         isMinionRestarted=true