Added sd-bus service example

Added obmc-phosphor-example-sdbus.
Added sdbus-service class for common logic.
diff --git a/common/recipes-phosphor/obmc-phosphor-fan/obmc-phosphor-fand.bb b/common/recipes-phosphor/obmc-phosphor-fan/obmc-phosphor-fand.bb
index c83e825..13c4b70 100644
--- a/common/recipes-phosphor/obmc-phosphor-fan/obmc-phosphor-fand.bb
+++ b/common/recipes-phosphor/obmc-phosphor-fan/obmc-phosphor-fand.bb
@@ -3,4 +3,4 @@
 PR = "r1"
 
 inherit obmc-phosphor-fan-mgmt
-inherit obmc-phosphor-c-daemon
+inherit obmc-phosphor-sdbus-service