GED EGM RECO as default + customizeOldEGReco

This PR is based on top of #1801 and is also built on top of 7_0_0_pre10.

You will need to manually download the new MVA weight file, for the classifiers, in the following packages:
RecoParticleFlow/PFTracking
RecoEgamma/ElectronIdentification

with the usual ```cat download.url | xargs wget```

For comparison purposes the default running mode of this PR should be a no-op to "GED mode" for #1801.
Likewise "OldEG" mode should be a no-op to the default running mode of #1801.

OldEG mode is activated by doing:
```runTheMatrix.py -s --useInput all  --command="--customise RecoEgamma/Configuration/customizeOldEGReco.customizeOldEGReco"```

@slava77 The default mode only runs one version of the of conversion tracking. Please confirm timing improvements. The OldEG mode runs both sets of conversion tracking now.
@nancymarinelli In default mode, standard reco::Photons no longer have conversion information. 
@franzoni All validation sequences (that I could find) have been updated to point at the new ged products. If there's anything deeper you need please let us know.

Still waiting on matrix tests on my side due to annoying silent failures... Will update as soon as I have that information.