messed up dataset names prevents caching of did lookups

[ivukotic]

If I look at the postgresdb datasets, I see things like this:

 rucio://mc20_13TeV.364157.Sherpa_221_NNPDF30NNLO_Wmunu_MAXHTPTV0_70_CFilterBVeto.deriv.DAOD_PHYSLITE.e5340_s3681_r13145_p6026?files=1
 rucio://mc20_13TeV.364157.Sherpa_221_NNPDF30NNLO_Wmunu_MAXHTPTV0_70_CFilterBVeto.deriv.DAOD_PHYSLITE.e5340_s3681_r13145_p6026?files=2
 rucio://mc20_13TeV:mc20_13TeV.345705.Sherpa_222_NNPDF30NNLO_ggllll_0M4l130.deriv.DAOD_PHYSLITE.e6213_s3681_r13167_p6026?files=1```

each time we append something to the dataset name it will do a new did lookup and it will fail as there is no such dataset. 
I also find it not at all clean way to pass parameters.

[ivukotic]

this will be solved with #767