Implement the DeleteAll interface

Implement the xyz.openbmc_project.Collection.DeleteAll
interface to delete all logging entries.

Change-Id: I007dd8408ebb4e30bf3d3a3c431d747248620aa4
Signed-off-by: Matt Spinler <spinler@us.ibm.com>
diff --git a/manager.cpp b/manager.cpp
index d47b3ad..45982fc 100644
--- a/manager.cpp
+++ b/manager.cpp
@@ -84,6 +84,11 @@
     }
 }
 
+void Manager::eraseAll()
+{
+    entries.clear();
+}
+
 void Manager::addInterface(const std::string& objectPath, InterfaceType type,
                            std::experimental::any& object)
 {