Monte Carlo for FeMtobarn processes

Current version

mcfm requires the following formulae to be installed:
lhapdf 6.2.1 PDF interpolation and evaluation
gcc 7.3.0_1 GNU compiler collection

Recent formula history

David Hall Fix warnings due to latest Homebrew formula standards.
David C Hall mcfm: fix audit (#116)
David Hall Travis-CI uses brew test-bot Copied .travis.yml from brew-tap-new script. This should make for quicker testing, because only the edited formula is tested. Also moved formulae to Formula folder.
David Hall mcfm: fix test
David Hall mcfm: 8.0, added OpenMP option

Formula code at GitHub