Revert "reversed change - does not compile on OSX/clang/boost1.54"
Revert "reversed change - does not compile on OSX/clang/boost1.54"

This reverts commit 2ea723e77452674a9e447c41169ba1e62e03436e.

Ubitrack/build_environment,Ubitrack/build_environment,Ubitrack/build_environment