changed the modules to use the new BACNet string types.

Modified the device object to handle having the string properties changed via WriteProperty service.
Updated the unit tests.
Updated the demo objects.

bacnet-stack/arf.h

@@ -37,6 +37,7 @@
 #include <stdint.h>
 #include <stdbool.h>
 #include "bacdcode.h"
+#include "bacstr.h"
 
 typedef struct BACnet_Atomic_Read_File_Data
 {
@@ -57,10 +58,7 @@ typedef struct BACnet_Atomic_Read_File_Data
       unsigned RecordCount; 
     } record;
   } type;
-  // These are used for the ACK portion
-  // Set them to an unused buffer for the decode to fill
-  uint8_t *fileData;
-  unsigned fileDataLength;
+  BACNET_OCTET_STRING fileData;
   bool endOfFile;
 } BACNET_ATOMIC_READ_FILE_DATA;