Added emulation for ZeroBias data, TandP data and MC + few useful tools

[davignon]

Hi,

This PR concerns the addition of emulation to the framework. This is useful to perform L1 studies.
Here is a verbatim of the addition and changes.

Added:

• plugins/ZeroBias.cc: plugin for emulation without RECO.
• python/zeroBias_cff.py: sequence for emulation without RECO (runs on RAW or GEN-SIM-RAW).
• test/reEmulL1_ZeroBias.py: config for emulation without RECO (runs on RAW or GEN-SIM-RAW).
• CreateFileList.C: tool to help prepare filelists.
• das_client.py: used by CreateFileList.C and python submitters to get list of files from DAS.
• submitOnTier3_reEmulL1.py: submitter for emulation of L1 (when including reco).
• submitOnTier3_reEmulL1_MC.py: submitter for emulation of L1 (when including reco). Specific to MC due to data structure. Could in principle be merged with previous.
• submitOnTier3_reEmulL1_zeroBias.py: submitter for emulation of L1 (when not including reco).

Modified:

• plugins/Ntuplizer.cc: small changes to adapt for emulation
• python/MCanalysis_cff.py: same
• python/tagAndProbe_cff.py: same
• reEmulL1.py: adapt for two-file solution
• test.py: minor changes

Thank you in advance for merging and let me know if some of this is unclear.