v4.0.1-sl5: SL5 legacy bugfix release

This is the latest SL5 release, including everything that was developed so far in SL5.

With respect to the previously announced v4.0-sl5, 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 #165)

To be used on top of CMSSW_6_1_1 (or any release with the same roofit and roostats versions) for SL5