Warning from genconfuser.py

The following discussion from !184 (merged) should be addressed:

• @rmatev started a discussion:

  @clemenci I think here something is not right here as we started to get a warning

  (build/Alignment/Escher)$ build/run genconfuser.py --build-dir build --root Alignment/Escher/python --output build/Alignment/Escher/genConfDir/Escher/Escher_user.confdb Escher Escher.Configuration 
  WARNING: Configurable class CountingPrescaler not in database

  I tried lhcb_add_confuser_dependencies(Alignment/TAlignment:TAlignment) locally but it didn't really help and the dependency seems missing.