Fix for eta 3 problem in HE 

Pedestal subtraction for the last HE rechits to cure the eta 3 problem

Currently all workflows fail with

    ----- Begin Fatal Exception 04-Nov-2014 18:29:33 CET-----------------------
    An exception of category 'ProductNotFound' occurred while
       [0] Processing run: 1 lumi: 1 event: 1
       [1] Running path 'reconstruction_step'
       [2] Calling event method for module PFRecHitProducer/'particleFlowRecHitHBHE'
    Exception Message:
    Principal::getByToken: Found zero products matching all criteria
    Looking for type: std::vector<reco::Vertex>
    Looking for module label: offlinePrimaryVertices
    Looking for productInstanceName: 

       Additional Info:
          [a] If you wish to continue processing events after a ProductNotFound exception,
    add "SkipEvent = cms.untracked.vstring('ProductNotFound')" to the "options" PSet in the configuration.

    ----- End Fatal Exception -------------------------------------------------

Without this pull request the generated reco file has offlinePrimaryVertices in it, so this module must be being run before the vertices are created.