Shashlik out of time pileup mitigation

Multifit for ecal pulse shapes backport from 7_something, and PF pileup mitigation changes.  Includes #5845.

@bachtis, I had to add a change to class checksums
@lgray, @bendavid, FYI
What SCRAM_ARCH and which IB are you using?  I get a compile error with no modification to the package, just checking it out on top of the IB:

    [grimes@lxplus0170 grimes]$ scram project CMSSW_6_2_X_SLHC_2014-10-21-0200
    [grimes@lxplus0170 grimes]$ cd CMSSW_6_2_X_SLHC_2014-10-21-0200/src/
    [grimes@lxplus0170 src]$ cmsenv
    [grimes@lxplus0170 src]$ echo $SCRAM_ARCH
    slc6_amd64_gcc472
    [grimes@lxplus0170 src]$ git-cms-init 
    <output trimmed>
    [grimes@lxplus0170 src]$ git-cms-addpkg AnalysisDataFormats/SUSYBSMObjects
    Checking out package AnalysisDataFormats/SUSYBSMObjects
    [grimes@lxplus0170 src]$ scram b -j 10
    <output trimmed>
    error: class 'susybsm::HSCPCaloInfo' has a different checksum for ClassVersion 11. Increment ClassVersion to 12 and assign it to checksum 2407040083
    gmake: *** [tmp/slc6_amd64_gcc472/src/AnalysisDataFormats/SUSYBSMObjects/src/AnalysisDataFormatsSUSYBSMObjects/libAnalysisDataFormatsSUSYBSMObjectsCapabilities.so] Error 1
    gmake: *** [There are compilation/build errors. Please see the detail log above.] Error 2