presence: Add sensor to redundancy policy api

Include a reference to the sensor changing state when sensor
implementations ping the policy object.

This allows policy logic based on multiple sensors, simultaneously.

Change-Id: I44cf00c7ecd220d0cc99e51ca6093bac6da7343c
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/presence/fallback.cpp b/presence/fallback.cpp
index 625d74a..7550c34 100644
--- a/presence/fallback.cpp
+++ b/presence/fallback.cpp
@@ -26,7 +26,7 @@
 namespace presence
 {
 
-void Fallback::stateChanged(bool present)
+void Fallback::stateChanged(bool present, PresenceSensor& sensor)
 {
     if (!present)
     {