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/dcmihandler.hpp b/dcmihandler.hpp
index 6e64faf..29757ff 100644
--- a/dcmihandler.hpp
+++ b/dcmihandler.hpp
@@ -1,5 +1,4 @@
-#ifndef __HOST_IPMI_DCMI_HANDLER_H__
-#define __HOST_IPMI_DCMI_HANDLER_H__
+#pragma once
 
 #include "nlohmann/json.hpp"
 
@@ -628,5 +627,3 @@
 } __attribute__((packed));
 
 } // namespace dcmi
-
-#endif