Add license to LoadPNG.h

OpenVR/TimestepData/LoadPNG.h

+/*
+# Copyright 2016-2018 The NOMAD Developers Group
+ #
+ # Licensed under the Apache License, Version 2.0 (the "License");
+ # you may not use this file except in compliance with the License.
+ # You may obtain a copy of the License at
+ #
+ #     http://www.apache.org/licenses/LICENSE-2.0
+ #
+ # Unless required by applicable law or agreed to in writing, software
+ # distributed under the License is distributed on an "AS IS" BASIS,
+ # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ # See the License for the specific language governing permissions and
+ # limitations under the License.
+*/
+
 #ifndef LOADPNG_H
 #define LOADPNG_H
 #include "NOMADVRLib/MyGL.h"
 
 GLuint LoadPNG (const char *image);
 
-#endif
\ No newline at end of file
+#endif