Update Sherpa to v2.2.7
This is based on the recent installation of Sherpa 2.2.7 by LCG in https://sft.its.cern.ch/jira/browse/SPI-1344 (being deployed on cvmfs right now).
This is based on the recent installation of Sherpa 2.2.7 by LCG in https://sft.its.cern.ch/jira/browse/SPI-1344 (being deployed on cvmfs right now).