Invalid branch content for mc truth branches in DV tutorial5

I noticed that the DV tutorial tutorial5_mctruth.py generate a tuple with invalid branch contents. In particular the branches with the mc truth information X_TRUEP and X_TRUEID are not filled correctly since their value are always nan and 0, respectively. The corresponding test pass, since it checks only if the tuple is not empty.

The idea is to fix the tutorial in order to have a working example and also improve the DV tests checking not only if the final tuple is filled but also the checking the validity of the values in the .root file.