Add preferred version 2.0.3. Added beta version. Added conflict with
gcc versions >= 5 when building with cuda@8 (which is currently the
only supported cuda version). Added cuda architecture variant. Added
comment about current lack of cuda@9 support.
* added relion v 2.1
* relion 2.1 - misssed comma
* relion now pulling from master branch - removed 2.03 - added cuda 8 as dependency given 9 does not yet work with relion per https://github.com/3dem/relion/issues/296
* Add universal build_type variant to CMakePackage
* Override build_type in some packages with different possible values
* Remove reference to no longer existent debug variant
* Update CBTF packages with new build_type variant
* Keep note on build size of LLVM
