Override setting Current mode property

When the Current mode property changes, the persisted value is updated.

Change-Id: I319fbe2afb8112f7425dc0a1d765fe8f1c408bae
Signed-off-by: Matthew Barth <msbarth@us.ibm.com>
diff --git a/control/zone.hpp b/control/zone.hpp
index 3774d76..73761d0 100644
--- a/control/zone.hpp
+++ b/control/zone.hpp
@@ -468,6 +468,15 @@
                                        const std::string& intf,
                                        int32_t depth);
 
+        /**
+         * @brief Overridden thermal object's set 'Current' property function
+         *
+         * @param[in] value - Value to set 'Current' to
+         *
+         * @return - The updated value of the 'Current' property
+         */
+        virtual std::string current(std::string value);
+
     private:
 
         /**