code-cleaning in RecoMET

add integration tests in RecoMET/METProducers

It tests if the following modules to produce various definition of METs run without an error:
genMetCalo, genMetCaloAndNonPrompt, genMetTrue, genMetIC5GenJets, met, metNoHF, metHO, metNoHFHO, metOpt, metOptNoHF, metOptHO, metOptNoHFHO, htMetAK5, corMetGlobalMuons, tcMet, tcMetCST, tcMetRft2, tcMetVedu, tcMetWithPFclusters, pfMet, pfClusterMet, pfChargedMET

It doesn't test if the contents are right.