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/sensordatahandler.hpp b/sensordatahandler.hpp
index 7185116..771303d 100644
--- a/sensordatahandler.hpp
+++ b/sensordatahandler.hpp
@@ -1,13 +1,12 @@
 #pragma once
 
+#include "sensorhandler.hpp"
 #include "types.hpp"
 #include "utils.hpp"
 
+#include <host-ipmid/ipmid-api.h>
 #include <math.h>
 
-#include "host-ipmid/ipmid-api.h"
-#include "sensorhandler.h"
-
 namespace ipmi
 {
 namespace sensor