Add SUSY-HIT

This adds [SUSY-HIT](http://www.itp.kit.edu/~maggie/SUSY-HIT/), which calculates particle spectrum and the decay widths and branching ratios of the Higgs bosons and supersymmetric particles.

There is one executable, `run`, and some input files. Since the executable only reads the input file in the same directory, it provides a `susyhit-1.4.tar.gz`, where the executable and the input files are contained all together.

It has been tested on both OS X and Linux.
Is this unpackPhase needed? By default, nix stdenv will unpack tarballed source and set its directory as `$sourceRoot` and then change the current directory to `$sourceRoot`.