fix list dataset with acquisition bug. YG

Manuel:

Would you please merge this, rebuit the rpm and test it before submitting the request to HTTP group?
This is the fix to a bug reported by Vincenzo Spinoso <vincenzo.spinoso@cern.ch>. 
https://cmsweb.cern.ch/dbs/prod/global/DBSReader/datasets?acquisition_era_name=Fall13
returns [], but data was in the DB.
Thanks,
Yuyi