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: I768b8efcac262ef07cf75f06486c6144c090e91a
diff --git a/callout.cpp b/callout.cpp
index 1d95036..cf88519 100644
--- a/callout.cpp
+++ b/callout.cpp
@@ -81,14 +81,14 @@
     callout.serialNumber(sn);
 }
 
-Callout::Callout(sdbusplus::bus::bus& bus, const std::string& objectPath,
+Callout::Callout(sdbusplus::bus_t& bus, const std::string& objectPath,
                  size_t id, uint64_t timestamp) :
     CalloutObject(bus, objectPath.c_str(), CalloutObject::action::defer_emit),
     entryID(id), timestamp(timestamp)
 {
 }
 
-Callout::Callout(sdbusplus::bus::bus& bus, const std::string& objectPath,
+Callout::Callout(sdbusplus::bus_t& bus, const std::string& objectPath,
                  const std::string& inventoryPath, size_t id,
                  uint64_t timestamp, const DbusPropertyMap& properties) :
     CalloutObject(bus, objectPath.c_str(), CalloutObject::action::defer_emit),