Remove CandRefHelper.cc, seems to be not used.

Spotted this file trying to fix some warnings going off when compiling on gcc490.
It gives a warning on this file of the kind "Unused function", but probably the compiler misunderstand the statement of the class thinking it's actually a function.
Previous compilers didn't spot this, @vadler should we remove this file or can you find a fix for it?
Merge pull request #2674 from degano/remove_candrefhelper_71Xgcc490

gcc 4.9.0 -- Remove CandRefHelper.cc, seems to be not used.