M tbtag

This PR makes few b-tagging modules multi-thread friendly, as requested by HLT people (cc: @fwyzard).

With the PR:
"fillDescriptions" starts to be used in:
    -JetTagProducer
    -SecondaryVertexProducer
    -SoftLepton
    -TrackIPProducer

EDProducers are switched from legacy to edm::stream in:
    -JetTagProducer
    -FastPrimaryVertexWithWeightsProducer
    -HLTDisplacedmumuVtxProducer
    -HLTmumutkVtxProducer

The fillDescriptions have been filled following:
RecoBTag/SoftLepton/python/softMuonTagInfos_cfi.py

RecoBTag/SecondaryVertex/python/secondaryVertexTagInfos_cfi.py

ImpactParameter/​python/​impactParameterTagInfos_cfi.py

RecoBTau/JetTagComputer/python/ImpactParameter/​python/​ combinedMVABJetTags_cfi.py
RecoBTau/JetTagComputer/python/ImpactParameter/​python/​ positiveCombinedMVABJetTags_cfi.py
RecoBTau/JetTagComputer/python/ImpactParameter/​python/​ negativeCombinedMVABJetTags_cfi.py

cc: @aclebihan @arizzi @imarchesini @acaudron  @ferencek  @wddgit

Cheers,
Silvio.
Oops, there is also a 3rd instance, 'ghhostTrackVertexTagInfos`, defined in https://github.com/cms-sw/cmssw/blob/CMSSW_7_3_0_patch1/RecoBTag/SecondaryVertex/python/ghostTrackVertexTagInfos_cfi.py So ignore my previous comments about `ghostTrackVertexTagInfos`. Sorry for the confusion.