examples: Add back examples using the async APIs

Add the examples back by using the new async API, support verification and
enroll for devices with own storage.

examples/cpp-test.cpp

@@ -6,6 +6,10 @@
 
 int main (int argc, char **argv)
 {
-	fp_init ();
+	FpContext *ctx;
+
+	ctx = fp_context_new ();
+	g_object_unref (ctx);
+
 	return 0;
 }