Enable pacparse in cmssw-tool-conf, needed for frontier_client

Signed-off-by: David Abdurachmanov <David.Abdurachmanov@cern.ch>
Backport git from CMSSW_7_0_X

Signed-off-by: David Abdurachmanov <David.Abdurachmanov@cern.ch>
Merge pull request #178 from davidlt/53x-osx106-git-pacparse-frontier_client

[CMSSW_5_3_X] Backport git and frontier_client from CMSSW_7_0_X