Update CONTRIBUTING.md

added contribution license
Update CONTRIBUTING.md
Add support for MPICH to ScaLAPACK easyblock
Update CONTRIBUTING.md

is in sync with the easybuild contributing.md now
Merge pull request #168 from JensTimmerman/contributor_license

Update CONTRIBUTING.md
Add support for ClangGcc to fortran Python package easyblock
Merge pull request #172 from gribozavr/clang-toolchains

Add support for MPICH to ScaLAPACK easyblock