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/image_manager.hpp b/image_manager.hpp
index 25f0ced..ca4d676 100644
--- a/image_manager.hpp
+++ b/image_manager.hpp
@@ -26,7 +26,7 @@
      *
      * @param[in] bus - The Dbus bus object
      */
-    explicit Manager(sdbusplus::bus::bus& bus) : bus(bus){};
+    explicit Manager(sdbusplus::bus_t& bus) : bus(bus){};
 
     /**
      * @brief Verify and untar the tarball. Verify the manifest file.
@@ -51,7 +51,7 @@
     std::map<std::string, std::unique_ptr<Version>> versions;
 
     /** @brief Persistent sdbusplus DBus bus connection. */
-    sdbusplus::bus::bus& bus;
+    sdbusplus::bus_t& bus;
 
     /** @brief The random generator to get the version salt */
     std::mt19937 randomGen{static_cast<unsigned>(