Add discard command

Change-Id: Ie2243188694657665240769d93b2835034e48c3a
diff --git a/src/sysrepo_access.hpp b/src/sysrepo_access.hpp
index fb1f713..13b4ace 100644
--- a/src/sysrepo_access.hpp
+++ b/src/sysrepo_access.hpp
@@ -36,6 +36,7 @@
     std::vector<std::string> listImplementedSchemas();
 
     void commitChanges() override;
+    void discardChanges() override;
 
     std::shared_ptr<Schema> schema();