move joinPaths to utils.cpp

Change-Id: I8012fa004d174ddf42086b109caab3f2d7857d1e
diff --git a/src/utils.hpp b/src/utils.hpp
new file mode 100644
index 0000000..54c455a
--- /dev/null
+++ b/src/utils.hpp
@@ -0,0 +1,10 @@
+/*
+ * Copyright (C) 2018 CESNET, https://photonics.cesnet.cz/
+ * Copyright (C) 2018 FIT CVUT, https://fit.cvut.cz/
+ *
+ * Written by Václav Kubernát <kubervac@fit.cvut.cz>
+ *
+*/
+#include <string>
+
+std::string joinPaths(const std::string& prefix, const std::string& suffix);