Fix parameter passing

[yalwan-iqvia]

It seems like some parameters were not being passed to dataset or booster.

Rather than trying to fix this by hand, I took advantage of the fact that LightGBM doesn't seem to warn if you pass all the parameters to both constructs, so I updated stringifyparams to just ignore the booster and model fields

I also took the opportunity to give it a kwarg to add verbosity and fix verbosity passing everywhere -- finally tests don't vomit output everywhere.

[yalwan-iqvia]

@chilledgeek @kd-iqvia PTAL