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: I41103c892db258a85640aa1442acd9a295c8a847
diff --git a/systemd_target_signal.hpp b/systemd_target_signal.hpp
index 61f3f06..e6bbcbe 100644
--- a/systemd_target_signal.hpp
+++ b/systemd_target_signal.hpp
@@ -30,7 +30,7 @@
 
     SystemdTargetLogging(const TargetErrorData& targetData,
                          const ServiceMonitorData& serviceData,
-                         sdbusplus::bus::bus& bus) :
+                         sdbusplus::bus_t& bus) :
         targetData(targetData),
         serviceData(serviceData), bus(bus),
         systemdJobRemovedSignal(
@@ -92,7 +92,7 @@
      * @param[in]  msg       - Data associated with subscribed signal
      *
      */
-    void systemdUnitChange(sdbusplus::message::message& msg);
+    void systemdUnitChange(sdbusplus::message_t& msg);
 
     /** @brief Wait for systemd to show up on dbus
      *
@@ -102,7 +102,7 @@
      * @param[in]  msg       - Data associated with subscribed signal
      *
      */
-    void processNameChangeSignal(sdbusplus::message::message& msg);
+    void processNameChangeSignal(sdbusplus::message_t& msg);
 
     /** @brief Systemd targets to monitor and error logs to create */
     const TargetErrorData& targetData;
@@ -111,7 +111,7 @@
     const ServiceMonitorData& serviceData;
 
     /** @brief Persistent sdbusplus DBus bus connection. */
-    sdbusplus::bus::bus& bus;
+    sdbusplus::bus_t& bus;
 
     /** @brief Used to subscribe to dbus systemd JobRemoved signals **/
     sdbusplus::bus::match_t systemdJobRemovedSignal;