v5.0.1 SLC6 release

This is the first good SLC6 release for HiggsAnalysis/CombinedLimit, that can be used on CMSSW_7_1_5 (or later 7.1.X) on the slc6_amd64_gcc481 architecture.

With respect to the previously announced v5.0, it fixes a bug in the code that warns about nuisance parameters close to their boundaries, which would under some circumstances cause a crash (PR #166)

It includes everything in the v4.0.1-sl5 release plus some pdfs needed for combination with ATLAS.