rename headers to match style

Moving headers from ".h" to ".hpp"

Reworked the header inclusion a bit so that host-ipmid is treated as a
library, and local headers aren't.

renamed apphandler.h => apphandler.hpp
renamed chassishandler.h => chassishandler.hpp
renamed globalhandler.h => globalhandler.hpp
renamed sensorhandler.h => sensorhandler.hpp
renamed storageaddsel.h => storageaddsel.hpp
renamed storagehandler.h => storagehandler.hpp
renamed systemintfcmds.h => systemintfcmds.hpp

Change-Id: I9d4ce3dd57e2e996800f9020a10cc10cdf2c3914
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/ipmisensor.cpp b/ipmisensor.cpp
index b3fac2c..de8b844 100644
--- a/ipmisensor.cpp
+++ b/ipmisensor.cpp
@@ -1,10 +1,10 @@
+#include "sensorhandler.hpp"
+
 #include <malloc.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <string.h>
 
-#include "sensorhandler.h"
-
 extern uint8_t find_type_for_sensor_number(uint8_t);
 
 struct sensorRES_t