Remove local Serialization.cc files as they conflict with the generated ones.

This PR for the BOOSTIO branch needs the scram config tag V05-01-22 to go in as well, otherwise the IB will break. The PR removes the local src/Serialization.cc files (which are now generated by scram) and changes the log level for the generating script to be more silent (warnings and errors only). It also adds back some declarations for transient members in CondFormats/DTObjects/interface/DTReadOutMapping.h which came in when merging with 7.1.x mainstream changes.