Added dynamic and static RAM file systems to use with file objects. (#1058)

* Added dynamic RAM file system to use with basic bacnet file object.

* Added static RAM file system to use with basic bacnet file object.

* Added check for read-only during AtomicWriteFile service API for BACnet File object.

* Change stm32f4xx example to use static RAM file system.

* Fixed bacfile_count() function return type

ports/stm32f4xx/device.c

@@ -31,6 +31,9 @@
 #include "bacnet/basic/object/mso.h"
 #include "bacnet/basic/object/msv.h"
 #include "bacnet/basic/object/program.h"
+#if defined(BACFILE)
+#include "bacnet/basic/object/bacfile.h"
+#endif
 #if (BACNET_PROTOCOL_REVISION >= 17)
 #include "bacnet/basic/object/netport.h"
 #endif
@@ -94,6 +97,11 @@ static struct my_object_functions {
         Program_Index_To_Instance, Program_Valid_Instance,
         Program_Object_Name, Program_Read_Property,
         Program_Write_Property, Program_Property_Lists},
+#if defined(BACFILE)
+    { OBJECT_FILE, bacfile_init, bacfile_count, bacfile_index_to_instance,
+        bacfile_valid_instance, bacfile_object_name, bacfile_read_property,
+        bacfile_write_property, BACfile_Property_Lists },
+#endif
 #if (BACNET_PROTOCOL_REVISION >= 17)
     { OBJECT_NETWORK_PORT, Network_Port_Init, Network_Port_Count,
         Network_Port_Index_To_Instance, Network_Port_Valid_Instance,