added test for input 0

test/fakultaet/test_fakultaet.c

@@ -0,0 +1,9 @@
+#include "unity.h"
+#include "fakultaet.h"
+
+void setUp(){}
+void tearDown(){}
+
+void test_fakultaetOf0() {
+	TEST_ASSERT_EQUAL_INT(1, fakultaet(0));
+}