sdbusplus: use shorter type aliases

The sdbusplus headers provide shortened aliases for many types.
Switch to using them to provide better code clarity and shorter
lines.  Possible replacements are for:
  * bus_t
  * exception_t
  * manager_t
  * match_t
  * message_t
  * object_t
  * slot_t

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I96286490697ce5d7fecc1c9c358f5f1d054137ec
diff --git a/download_manager_main.cpp b/download_manager_main.cpp
index c61e185..3656f8c 100644
--- a/download_manager_main.cpp
+++ b/download_manager_main.cpp
@@ -9,7 +9,7 @@
     auto bus = sdbusplus::bus::new_default();
 
     // Add sdbusplus ObjectManager.
-    sdbusplus::server::manager::manager objManager(bus, SOFTWARE_OBJPATH);
+    sdbusplus::server::manager_t objManager(bus, SOFTWARE_OBJPATH);
 
     phosphor::software::manager::Download manager(bus, SOFTWARE_OBJPATH);