actions: Add destroy action

Add an action to destroy an object on signal match.

Change-Id: I23fb160bcf7507d0d0a5f2d82f1cfb24131adf76
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/manager.cpp b/manager.cpp
index 6c15bf0..d77f128 100644
--- a/manager.cpp
+++ b/manager.cpp
@@ -160,6 +160,12 @@
     }
 }
 
+void Manager::destroyObject(const char *path)
+{
+    std::string p{path};
+    _refs.erase(_root + p);
+}
+
 #include "generated.hpp"
 
 } // namespace manager