attach the sd bus to sd_event to receive signals

Registering for property change signals for FRU inventory
data so notification is required.

Change-Id: I2dfee62d32b5b0726faa4643ee1efe9718424a61
Signed-off-by: Marri Devender Rao <devenrao@in.ibm.com>
diff --git a/main.cpp b/main.cpp
index e26bcda..842f098 100644
--- a/main.cpp
+++ b/main.cpp
@@ -30,6 +30,7 @@
         sol::Manager&> singletonPool(manager, table, loop, solManager);
 
 sd_bus* bus = nullptr;
+
 FILE* ipmidbus = nullptr;
 unsigned short g_sel_reserve = 0xFFFF;
 sd_bus_slot* ipmid_slot = nullptr;