presence: Add sensor comparison

Add a basic comparison operator for presence sensors.

Change-Id: Ib147fd24f6e9ea1daf5f2b0b71943e0b4c96a8b7
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/presence/Makefile.am b/presence/Makefile.am
index db7e459..e144858 100644
--- a/presence/Makefile.am
+++ b/presence/Makefile.am
@@ -8,6 +8,7 @@
 	fallback.cpp \
 	fan.cpp \
 	gpio.cpp \
+	psensor.cpp \
 	tach.cpp \
 	tach_detect.cpp