added ebuild for Open MPI 1.7.3
refactored CUDA use flag handling
Merge https://github.com/gentoo-science/sci
merge
removed superfluous die commands after emake
Merge https://github.com/gentoo-science/sci
Merge branch 'gentryx-master'

* gentryx-master:
  removed superfluous die commands after emake
  refactored CUDA use flag handling
  added ebuild for Open MPI 1.7.3