Add discard command

Change-Id: Ie2243188694657665240769d93b2835034e48c3a
diff --git a/src/datastore_access.hpp b/src/datastore_access.hpp
index 7259273..9cd6a70 100644
--- a/src/datastore_access.hpp
+++ b/src/datastore_access.hpp
@@ -25,4 +25,5 @@
     virtual void deletePresenceContainer(const std::string& path) = 0;
 
     virtual void commitChanges() = 0;
+    virtual void discardChanges() = 0;
 };