Fixed issues with how we get the file store header size.

test/filestoreio.cpp

@@ -15,6 +15,7 @@ int main() {
 	uint8_t volume[size];
 	char out[6];
 	uint32_t err;
+	FileStore32::format(volume, size);
 	FileStore32 fs(volume, volume + size, &err);
 
 	fs.write(42, (void*) "Hello", 6);

test/format.cpp

@@ -13,7 +13,7 @@ int main() {
 	const auto size = 1 << 16;
 	uint8_t volume[size];
 	uint32_t err;
-	FileStore32::format(volume, size, false);
+	FileStore32::format(volume, size);
 	FileStore32(volume, volume + size, &err);
 	return err;
 }