MINOR: lua: add uuid to the Class Proxy

the proxy UUID parameter is not set in the Lua Proxy Class.
This patches adds it.
diff --git a/doc/lua-api/index.rst b/doc/lua-api/index.rst
index 822f8bc..96367f6 100644
--- a/doc/lua-api/index.rst
+++ b/doc/lua-api/index.rst
@@ -823,6 +823,10 @@
 
   Contain the name of the proxy.
 
+.. js:attribute:: Proxy.uuid
+
+  Contain the unique identifier of the proxy.
+
 .. js:attribute:: Proxy.servers
 
   Contain an array with the attached servers. Each server entry is an object of
diff --git a/src/hlua_fcn.c b/src/hlua_fcn.c
index 2ae1bbb..9a7e657 100644
--- a/src/hlua_fcn.c
+++ b/src/hlua_fcn.c
@@ -781,6 +781,12 @@
 	lua_pushstring(L, px->id);
 	lua_settable(L, -3);
 
+	/* Add proxy uuid. */
+	lua_pushstring(L, "uuid");
+	snprintf(buffer, sizeof(buffer), "%d", px->uuid);
+	lua_pushstring(L, buffer);
+	lua_settable(L, -3);
+
 	/* Browse and register servers. */
 	lua_pushstring(L, "servers");
 	lua_newtable(L);