vlan: Modify create method to return an ObjectPath

This will be nice to have for ipmid so that it can easily figure out the
path of the new vlan object when it creates one.

Change-Id: I6b93c5e64499c0cb9e36e8354eda6089bfd6d6c9
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/network_manager.cpp b/network_manager.cpp
index 4483631..fa5da0f 100644
--- a/network_manager.cpp
+++ b/network_manager.cpp
@@ -176,9 +176,9 @@
         bus, objPath.string(), *this);
 }
 
-void Manager::vLAN(IntfName interfaceName, uint32_t id)
+ObjectPath Manager::vLAN(IntfName interfaceName, uint32_t id)
 {
-    interfaces[interfaceName]->createVLAN(id);
+    return interfaces[interfaceName]->createVLAN(id);
 }
 
 void Manager::reset()