Backport pacparser and frontier_client from CMSSW_7_0_X.

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 #176 from davidlt/53x-stable-git-frontier_client-pacparser

[CMSSW_5_3_] Backport git, pacparser and frontier_client from CMSSW_7_0_X.