fix $MODULEPATH extensions for Clang/CUDA, include versionsuffix in module subdir

This should fix the open issues with using goolfc or cgoolf together with HierarchicalMNS, as discussed in https://github.com/hpcugent/easybuild-easyconfigs/issues/1098 (reported by @kcgthb)

It also makes sure that the versionsuffix is included in the module subdir, which is important for e.g. `icc` and `ifort` included in `intel/2014b`, which have a `-GCC-4.x.y` versionsuffix.

https://github.com/hpcugent/easybuild-easyconfigs/pull/1106 is also required to fix the issues with `goolfc`

@wpoely86: please review?