Add Shashlik to METAlgorithm for Phase2

For Phase2 SHCAL, the reco step will have the following warning:
%MSG-w SignCaloSpecificAlgo:  METProducer:metNoHF 30-Jul-2014 14:46:45 CDT  Run: 1 Event: 1665
 ECAL tower cell not assigned to an ECAL subdetector!!!
%MSG

This is a quick fix, which will simply suppress the above warning.
However, it won't provide a correct MET significance calculation
as we don't have the resolution per Shashlik tower.
Merge pull request #4838 from zhenbinwu/JetMET_TP_SLHC16

Add Shashlik to METAlgorithm for Phase2